Rad Onc Boards: Staging → Treatment Decision Points, Doses & OARs

Purpose. High-yield review organized around the question "where does staging change what I do?" For each of the 8 ABR clinical categories: (1) the staging variables that flip the paradigm, (2) the RT prescription (dose/fractionation) by scenario, and (3) OAR constraints to memorize. Based on NCCN/ASTRO guidance, QUANTEC/HyTEC, and landmark trial data. Designed as a memorization aid for boards and trainee education; verify patient-care decisions against NCCN and site-specific clinical practice guidance.

How to read the tables. Stage/variable is the trigger; treatment is what changes. Doses are standard-of-care defaults (not exhaustive of all acceptable regimens). OAR numbers are the commonly-cited constraints; for SBRT, TG-101/AAPM values are assumed unless noted.

Staging system framework: Staging language is chosen for board-style decision-making and landmark-trial interpretation. AJCC Version 9 applies to several included sites, including nasopharynx, HPV-associated oropharynx, salivary glands, lung, thymus, pleural mesothelioma, anus, cervix, vulva, and CNS. Older AJCC 8 or FIGO 2009 terminology is retained where landmark trials and classic board-style datasets use it. Version-specific changes that alter management are highlighted in the relevant sections.

Universal OAR Cheat Sheet (conventional fractionation, ~2 Gy/fx)

SBRT quick-hit (3 fx / 5 fx): Cord 18/23 Gy max · Esophagus 25.2/32.5 · Brachial plexus 22/27 · Heart 30/38 · Great vessels 45/53 · Trachea/bronchus 30/32 · Stomach 22.5/32 · Duodenum 22.5/32 · Liver (700 cc spared) <15/<21 · Kidney (200 cc spared) <8.4/<10.6.

1. CENTRAL NERVOUS SYSTEM

Note on staging: Primary CNS tumors are not staged by TNM. Treatment decisions use WHO 2021 grade (driven by molecular markers), resection extent (GTR/STR/biopsy), and patient factors (age, KPS). Brain metastases use number/size/KPS/DS-GPA.

Gliomas (WHO 2021 — molecular drives everything)

Grading essentials (WHO 2021):

• Grade 2 (LGG): Diffuse astrocytoma IDH-mut, Oligodendroglioma IDH-mut/1p19q-codel.
• Grade 3: Anaplastic astrocytoma IDH-mut, Anaplastic oligodendroglioma.
• Grade 4: Glioblastoma IDH-wildtype; or Astrocytoma IDH-mut Grade 4 (formerly "secondary GBM"); presence of CDKN2A/B homozygous deletion upgrades IDH-mut astrocytoma to grade 4 even without necrosis/microvascular proliferation.
• MGMT methylation predicts TMZ benefit (especially elderly).

Margins: GBM — GTV = T1-enhance + cavity; CTV1 = +2 cm (includes FLAIR) to 46 Gy, CTV2 = +2 cm around enhance to 60 Gy (RTOG). EORTC single-volume: GTV+2 cm to 60.

Meningioma

Brain metastases

SRS dose (RTOG 90-05): <2 cm → 24 Gy; 2–3 cm → 18 Gy; 3–4 cm → 15 Gy. Fractionated SRS (FSRT): 27/3 or 30/5 for larger/cavity. WBRT: 30/10 (standard) or 20/5 (poor prognosis).

Other CNS

• Pituitary adenoma post-op persistent/growing: 45–50.4/25–28 or SRS 15–18 Gy (secretory: higher, 20–25 Gy SRS; avoid optics <8–10 Gy single fx).
• Vestibular schwannoma: SRS 12–13 Gy (hearing preservation) or FSRT 50/25.
• Craniopharyngioma (adult): 54/30 post-op.
• Ependymoma: 54–59.4 to tumor bed; CSI if disseminated.
• Medulloblastoma (adult, avg risk): CSI 23.4 Gy + posterior fossa/tumor bed boost to 54.

CNS OAR (memorize)

Brainstem 54 Gy max (surface 60) · Optic chiasm/nerves 54 Gy max · Cord 45 Gy · Cochlea mean 35–45 · Hippocampus (WBRT-HA) D100% <9, Dmax <16 · Lens <7 · Retina <45 · Lacrimal gland <30.

SRS single fraction: optics <8–10 Gy, brainstem <12.5, cord <12–14.

2. HEAD AND NECK (AJCC 8 / Version 9 framework — p16 changed everything in oropharynx)

Oropharynx — p16+ vs p16− uses DIFFERENT staging systems

AJCC 8 — p16+ oropharynx clinical T:

• T1: ≤2 cm
• T2: >2–4 cm
• T3: >4 cm OR extension to lingual surface of epiglottis
• T4: Moderately advanced — invades larynx, extrinsic tongue muscle, medial pterygoid, hard palate, or mandible and beyond (no T4a/b subdivision for p16+)

p16+ clinical N:

• N0: No nodes
• N1: Ipsilateral node(s), all ≤6 cm
• N2: Contralateral or bilateral nodes, all ≤6 cm
• N3: Any node >6 cm
• ENE is NOT used in p16+ clinical staging

p16+ clinical stage: T1–2 N0–N1 = I; T1–2 N2 or T3 N0–2 = II; T4 or N3 = III; M1 = IV.

AJCC 8 — p16− oropharynx (and most other H&N sites) T:

• T1: ≤2 cm
• T2: >2–4 cm
• T3: >4 cm OR extension to lingual epiglottis
• T4a: Moderately advanced local — larynx, extrinsic tongue muscle, medial pterygoid, hard palate, mandible
• T4b: Very advanced — lateral pterygoid, pterygoid plates, lateral nasopharynx, skull base, or encases carotid

p16− N (clinical) — ENE matters:

• N1: Single ipsi ≤3 cm, ENE(−)
• N2a: Single ipsi 3–6 cm ENE(−) or single ipsi ≤3 cm ENE(+)
• N2b: Multiple ipsi ≤6 cm ENE(−)
• N2c: Bilateral/contralateral ≤6 cm ENE(−)
• N3a: Any >6 cm ENE(−)
• N3b: Any clinically overt ENE(+)

De-escalation principle: Outside a trial, do not de-escalate definitive p16+ chemoRT. NRG-HN005 closed for futility: neither experimental arm met non-inferiority versus 70 Gy + cisplatin. Two-year PFS was 98.1% with 70 Gy + cisplatin, 88.6% with 60 Gy + cisplatin, and 90.3% with 60 Gy + nivolumab. Standard definitive treatment remains 70 Gy + concurrent cisplatin for appropriate candidates.

Nasopharynx

AJCC 8 NPC T:

• T1: Confined to nasopharynx, oropharynx, or nasal cavity (no parapharyngeal)
• T2: Parapharyngeal extension or medial/lateral pterygoid or prevertebral muscle
• T3: Bony structures of skull base/cervical vertebrae, pterygoid structures, or paranasal sinuses
• T4: Intracranial, cranial nerve, hypopharynx, orbit, parotid, or extension beyond lateral pterygoid muscle

NPC N (unique to NPC):

• N1: Unilateral ≤6 cm above caudal border of cricoid or unilateral/bilateral retropharyngeal ≤6 cm
• N2: Bilateral ≤6 cm above cricoid
• N3: >6 cm OR extension below caudal border of cricoid

NPC stage: T1 N0 = I; T0–1 N1 or T2 N0–1 = II; T3 or N2 = III; T4 or N3 = IVA.

Dose: 70 / 33–35 to GTV, 59.4–63 intermediate, 54 elective. Always treat bilateral necks + retropharyngeal.

Larynx

AJCC 8 — Glottic T (memorize: mobility is the hinge):

• Tis: carcinoma in situ
• T1: Limited to vocal cord(s), normal mobility (T1a = one cord; T1b = both cords)
• T2: Extension to supraglottis or subglottis, or impaired cord mobility
• T3: Vocal cord fixation, or invades paraglottic space, inner thyroid cartilage, or postcricoid
• T4a: Through outer cortex of thyroid cartilage, or invades beyond larynx (trachea, strap muscles, thyroid, esophagus)
• T4b: Prevertebral space, mediastinum, or encases carotid

Supraglottic T (briefly): T1 one subsite normal mobility · T2 >1 subsite or adjacent supraglottic/glottis without fixation · T3 fixation or pre-epiglottic space/paraglottic/inner cartilage · T4a/b as above.

N (non-NPC H&N, same as p16−): as listed under Oropharynx above.

Oral cavity

Primary surgery → PORT indications same as oropharynx. Definitive RT only if unresectable.

Salivary gland

Post-op RT indications: high grade, T3–4, + margin, PNI, LVSI, N+. Dose 60–66 / 30–33. Consider neutrons or PBT for unresectable.

Unknown primary

Bilateral neck + mucosal (NPX, OPX, HPX) RT, or ipsilateral neck if p16+ level II (tailored).

H&N OAR

Parotid mean <26 (one <20 ideal) · Oral cavity mean <30–35 · Larynx mean <35–45 (glottic CA primary: no constraint on PTV) · Pharyngeal constrictors mean <50–55 · Cord 45 max · Brainstem 54 max · Cochlea mean <35–45 · Brachial plexus <66 · Mandible <70, V60<5 cc (ORN) · Esophagus mean <30 for DIP.

3. THORACIC

NSCLC (AJCC Version 9; AJCC 8 framework largely preserved)

AJCC Version 9 refinements: T descriptors are largely unchanged from AJCC 8. The refinements to memorize are N2a single-station vs N2b multistation ipsilateral mediastinal/subcarinal disease, and M1c1 multiple extrathoracic metastases in one organ system vs M1c2 multiple organ systems.

T (size-based + invasion):

• T1a: ≤1 cm
• T1b: >1 to ≤2 cm
• T1c: >2 to ≤3 cm
• T2a: >3 to ≤4 cm or visceral pleura, main bronchus (not carina), lobar atelectasis
• T2b: >4 to ≤5 cm
• T3: >5 to ≤7 cm or separate nodule same lobe or chest wall/parietal pericardium/phrenic n.
• T4: >7 cm or separate nodule different ipsilateral lobe or invades diaphragm/mediastinum/heart/great vessels/trachea/esophagus/RLN/vertebral body/carina

N:

• N0: No nodal
• N1: Ipsilateral peribronchial/hilar
• N2: Ipsilateral mediastinal/subcarinal; N2a = single station, N2b = multiple stations
• N3: Contralateral mediastinal/hilar, any scalene or supraclavicular

M:

• M1a: Contralateral lung nodule, pleural/pericardial nodules or malignant effusion
• M1b: Single extrathoracic met (single organ)
• M1c: Multiple extrathoracic mets; M1c1 = single organ system, M1c2 = multiple organ systems

Key stage groupings:

• IA1/IA2/IA3: T1a/b/c N0 · IB: T2a N0 · IIA: T2b N0 · IIB: T1–2 N1 or T3 N0
• IIIA: T1–2 N2, T3 N1, T4 N0–1 · IIIB: T1–2 N3, T3–4 N2 · IIIC: T3–4 N3
• IVA: M1a or M1b · IVB: M1c

SBRT BED10 ≥100 is the efficacy threshold for peripheral. Elective nodal irradiation is NOT used in NSCLC chemoRT (involved-field only).

SCLC

Staging (historical VALG, still clinically dominant):

• Limited stage (LS): Disease confined to one hemithorax, encompassable within a single radiation port (includes ipsilateral hilar, bilateral mediastinal, ipsilateral supraclavicular; malignant pleural effusion = extensive per most).
• Extensive stage (ES): Anything beyond — contralateral lung/hilum, distant mets, malignant effusion.
• AJCC 8 also applies (I–IV, same T/N as NSCLC), but LS generally = stage I–IIIC.

Other thoracic

• Thymoma (Masaoka-Koga): Stage I obs post-complete resection; II/III PORT 45–50 / post-op; unresectable/R2 definitive 60–70.
• Mesothelioma: Trimodality (EPP + hemithoracic RT 54/30) or lung-sparing IMRT after P/D; palliative.
• Esophagus: see GI.

Thoracic OAR (QUANTEC)

Lungs (−GTV): V20 ≤30–35%, MLD ≤20 Gy (pneumonitis <20%) · Heart: mean <26, V30 <46% · Cord 45–50 · Esophagus mean <34, V60 <17%, V35 <50% · Brachial plexus <66 · Bronchial tree <80 (SBRT: 4 cc <18 Gy in 3 fx, ultracentral protocol-specific).

SBRT 5-fx: Cord 23 max · Trachea/major bronchus 32 max · Esophagus 32.5 max · Brachial plexus 27 · Heart/pericardium 38 · Great vessels 53 · Skin 32.

4. BREAST (AJCC 8 added prognostic stage — but clinical/anatomic stage still drives treatment)

AJCC 8 — Breast T (by size):

• Tis: DCIS (LCIS removed from Tis in AJCC 8) · Tis (Paget): Paget's without underlying invasive/DCIS
• T1mi: ≤1 mm
• T1a: >1–5 mm · T1b: >5–10 mm · T1c: >10–20 mm
• T2: >20–50 mm
• T3: >50 mm
• T4a: Chest wall (not pec major alone)
• T4b: Skin ulceration, ipsilateral satellite skin nodules, or edema (peau d'orange)
• T4c: T4a + T4b
• T4d: Inflammatory carcinoma (clinicopathologic dx)

N (clinical):

• N1: Movable ipsilateral level I–II axillary
• N2a: Fixed/matted ipsi level I–II · N2b: Ipsilateral internal mammary without axillary
• N3a: Ipsilateral infraclavicular (level III axillary)
• N3b: Ipsilateral internal mammary with axillary (level I–II)
• N3c: Ipsilateral supraclavicular

N (pathologic) — critical for PMRT/RNI decisions:

• pN0(i+): ITCs ≤0.2 mm · pN1mi: micromets >0.2 to ≤2 mm · pN1a: 1–3 nodes · pN2a: 4–9 nodes · pN3a: ≥10 nodes or infraclavicular

Stage quick-glance: I (T1 N0) · IIA (T0–1 N1 / T2 N0) · IIB (T2 N1 / T3 N0) · IIIA (T0–2 N2 / T3 N1–2) · IIIB (T4 any N / any T N2 w/ T4) · IIIC (any T N3) · IV (M1).

Key decision points

Treatment scenarios

Omission of RT

• Luminal A, ≥65, pT1N0, ER+ on endocrine → PRIME II, LUMINA — can omit WBI.
• DCIS low-risk (size <2.5, grade 1–2, margin ≥3 mm, age >50) → consider omission.

Breast OAR

Heart mean <4 Gy (goal <3; DIBH for L-sided) · LAD max <20 · Ipsilateral lung V20 <15–20% (WBI), <35% (PMRT+RNI) · Contralateral breast mean <3 Gy · Contralateral lung V5 <10% · Brachial plexus <60–66 · Humeral head <50.

5. GASTROINTESTINAL

Esophagus

AJCC 8 — Esophagus T (depth of invasion; SCC and adeno staged separately but T is shared):

• Tis: HGD
• T1a: Lamina propria or muscularis mucosae
• T1b: Submucosa
• T2: Muscularis propria
• T3: Adventitia (no serosa on most of esophagus)
• T4a: Resectable — pleura, pericardium, azygos, diaphragm, or peritoneum
• T4b: Unresectable — aorta, vertebral body, trachea

N (counts of regional nodes):

• N0: 0 · N1: 1–2 · N2: 3–6 · N3: ≥7

Stage grouping distinction: Squamous uses location + grade in stage grouping; adenocarcinoma uses grade only (AJCC 8).

Gastric

AJCC 8 — Gastric T (depth-based, analogous to esophagus but note T4a serosa):

• Tis: HGD / carcinoma in situ (intraepithelial, no lamina propria invasion)
• T1a: Lamina propria or muscularis mucosae
• T1b: Submucosa
• T2: Muscularis propria
• T3: Subserosal connective tissue (no visceral peritoneum)
• T4a: Serosa (visceral peritoneum)
• T4b: Adjacent structures (spleen, transverse colon, liver, diaphragm, pancreas, abdominal wall, adrenal, kidney, small bowel, retroperitoneum)

N (node counts):

• N1: 1–2 · N2: 3–6 · N3a: 7–15 · N3b: ≥16

Minimum 16 nodes required for adequate staging (driver of INT-0116 adjuvant chemoRT indication).

• Resectable: Perioperative FLOT preferred (MAGIC/FLOT); post-op chemoRT (INT-0116) if R1/inadequate nodes: 45 / 25 + 5FU.
• Unresectable: chemoRT 45–50.4 + 5FU.

Pancreas

AJCC 8 — Pancreas T (SIZE-based since AJCC 8 — major change from AJCC 7):

• Tis: In situ (includes high-grade PanIN, IPMN with HGD, ITPN, MCN with HGD)
• T1a: ≤0.5 cm · T1b: >0.5 to <1 cm · T1c: 1 to ≤2 cm
• T2: >2 to ≤4 cm
• T3: >4 cm
• T4: Involves celiac axis, SMA, or common hepatic artery (regardless of size) → historically defines unresectable; selected locally advanced cases may be treated as borderline after multidisciplinary review

N (nodal count):

• N0: 0 · N1: 1–3 regional · N2: ≥4 regional

Resectability criteria (NCCN — independent of T stage, drives treatment): | Category | Arterial | Venous | |---|---|---| | Resectable | No contact with celiac/SMA/CHA | No contact with SMV/PV, or ≤180° contact without vein contour irregularity | | Borderline resectable | Solid tumor contact with CHA without extension to celiac/bifurcation; SMA/celiac ≤180°; variant anatomy | SMV/PV >180°, contour irregularity, thrombosis (reconstructable); IVC contact | | Locally advanced (unresectable) | SMA/celiac >180°; aortic involvement | Unreconstructable SMV/PV |

• Resectable/borderline: Neoadjuvant FOLFIRINOX ± chemoRT (50.4/28) → surgery. PREOPANC showed benefit.
• Locally advanced unresectable: chemo → SBRT 33–40 / 5 or chemoRT 50.4/28.
• Post-op: chemoRT 45–50.4 (controversial, RTOG 0848 pending mature).

Rectal (TNT is the modern default)

AJCC 8 — Rectal T:

• Tis: Intraepithelial or lamina propria
• T1: Submucosa
• T2: Muscularis propria
• T3: Through muscularis propria into pericolorectal tissues (the T3 threshold that triggers TNT)
• T4a: Penetrates visceral peritoneum
• T4b: Invades/adherent to adjacent organ or structure

N:

• N1a: 1 node · N1b: 2–3 nodes · N1c: tumor deposits in subserosa/mesocolic tissue without regional nodal met
• N2a: 4–6 nodes · N2b: ≥7 nodes

MRI-based high-risk features (NCCN/EURECCA) independent of T stage:

• Extramural venous invasion (EMVI+)
• Involved/threatened mesorectal fascia (MRF+ if ≤1 mm)
• Lateral pelvic nodes
• Low rectal tumors

→ These push toward TNT even if borderline T stage.

Dose painting for boost: 45 Gy elective + boost to 50.4–54 primary.

Anal (Nigro)

AJCC 8 — Anal canal T (pure size, unlike most other GI):

• Tis: HSIL / AIN III
• T1: ≤2 cm
• T2: >2 to ≤5 cm (boards: >4 cm within T2 is the boost-dose threshold per RTOG 0529)
• T3: >5 cm
• T4: Invades adjacent organ (vagina, urethra, bladder) — perianal skin, subcutaneous tissue, or sphincter muscle alone does NOT qualify as T4

N (drainage-based):

• N1a: Inguinal, mesorectal, or internal iliac
• N1b: External iliac
• N1c: External iliac + any N1a

• T1 N0 low-risk: surgery alone acceptable (small).
• All others (most): definitive chemoRT with 5FU + mitomycin-C (RTOG 98-11 MMC > cisplatin).

HCC

AJCC 8 — HCC T (radiation oncology cares most about BCLC + Child-Pugh, but know T):

• T1a: Solitary ≤2 cm
• T1b: Solitary >2 cm without vascular invasion
• T2: Solitary >2 cm with vascular invasion or multiple all ≤5 cm
• T3: Multiple tumors at least one >5 cm
• T4: Major branch portal/hepatic vein or invades adjacent organ (not gallbladder) or perforation of visceral peritoneum

BCLC (drives therapy more than AJCC):

• 0 (very early): Single ≤2 cm, PS 0, Child-Pugh A → ablation/resection
• A (early): Single or ≤3 nodules ≤3 cm, PS 0 → resection/ablation/transplant (Milan); SBRT if inoperable
• B (intermediate): Multinodular, PS 0 → TACE; SBRT if refractory
• C (advanced): Vascular invasion or extrahepatic → systemic (atezo/bev); SBRT in select
• D (terminal): PS >2 / Child-Pugh C → BSC

• Child-Pugh A: SBRT 40–50 / 5 (selective); TACE; transplant per Milan.
• Child-Pugh B: dose-reduce, careful mean liver dose.

Cholangiocarcinoma / Gallbladder

• Post-op adjuvant chemoRT 45–50.4 for R1 or N+.
• SBRT for unresectable.

GI OAR

Cord 45 · Kidney bilat mean <18, V20 <32% each · Liver mean <30 (conventional), <20 (SBRT, ≥700 cc spared) · Stomach/duodenum Dmax <54, V50 <5% · Small bowel V15 <120 cc or V45 <195 cc loops · Rectum V50 <50%, V70 <20% · Femoral heads V50 <5% · Bladder V65 <50%.

Liver SBRT: 700 cc of normal liver should receive <15 Gy (3 fx) / <21 Gy (5 fx).

6. GENITOURINARY

Prostate — risk group drives everything

AJCC 8 — Prostate cT:

• T1: Clinically inapparent (not palpable, not visible)
• T1a: Incidental on TURP, ≤5% of tissue
• T1b: Incidental on TURP, >5%
• T1c: Needle biopsy only (elevated PSA)
• T2: Confined to prostate, palpable
• T2a: ≤½ of one lobe · T2b: >½ of one lobe · T2c: both lobes
• T3a: Extracapsular extension (uni- or bilateral) or microscopic bladder neck invasion
• T3b: Seminal vesicle invasion
• T4: Fixed or invades adjacent structures (external sphincter, rectum, bladder, levator, pelvic wall)

N: N1 = regional pelvic nodal involvement. M: M1a = non-regional nodes · M1b = bone · M1c = other (visceral).

NCCN risk groups:

• Very low: T1c, GS 6, PSA <10, <3 cores + <50% each, PSAD <0.15
• Low: T1–T2a, GS 6, PSA <10
• Favorable intermediate: 1 IR factor, % pattern 4 <50%, ≤50% cores
• Unfavorable intermediate: ≥2 IR factors OR GS 4+3 OR ≥50% cores
• High: T3a OR GS 8–10 OR PSA >20
• Very high: T3b–T4, primary 5, >4 cores GS 8–10

Key mod-hypofrac: CHHiP 60/20, PROFIT 60/20, RTOG 0415. SBRT: HYPO-RT-PC 42.7/7; PACE-B 36.25/5. Pelvic node dose: 45–50.4 Gy (POP-RT used 50/25).

Bladder

AJCC 8 — Bladder T (the muscularis propria line is everything):

• Ta: Non-invasive papillary
• Tis: Carcinoma in situ ("flat tumor")
• T1: Invades subepithelial connective tissue (lamina propria)
• T2a: Superficial muscularis propria (inner half) → muscle-invasive begins here
• T2b: Deep muscularis propria (outer half)
• T3a: Microscopic perivesical invasion
• T3b: Macroscopic perivesical (extravesical mass)
• T4a: Invades prostatic stroma, seminal vesicles, uterus, or vagina — still potentially resectable/curable
• T4b: Invades pelvic wall or abdominal wall — unresectable

N: N1 single true pelvic · N2 multiple true pelvic · N3 common iliac.

Testicular Seminoma

AJCC 8 — Testis T (after orchiectomy — pT):

• pT1: Limited to testis/epididymis, no LVI, may invade tunica albuginea (not tunica vaginalis)
• pT1a: <3 cm · pT1b: ≥3 cm (seminoma only)
• pT2: LVI or invades tunica vaginalis or hilar soft tissue/epididymis with LVI
• pT3: Spermatic cord
• pT4: Scrotum

N (by size AND number — nodal size matters most):

• N1: ≤2 cm and ≤5 nodes
• N2: >2–5 cm or >5 nodes or extranodal extension
• N3: >5 cm

S (serum tumor markers) — affects stage: S0 normal · S1/S2/S3 based on LDH, hCG, AFP (AFP should be normal in pure seminoma — elevated AFP = non-seminoma).

Stage groupings (clinical):

• IA: pT1 N0 M0 S0 · IB: pT2–4 N0 M0 S0 · IS: N0 M0 elevated markers
• IIA: N1 S0–1 · IIB: N2 S0–1 · IIC: N3 S0–1
• III: M1 or S2–3

• Stage I: Surveillance preferred; alternatives carboplatin × 1 or PA strip RT 20 Gy / 10.
• Stage IIA: PA + ipsilateral iliac (dog-leg) 20 Gy + 10 Gy boost (30 total).
• Stage IIB (≤5 cm): Dog-leg 20 + 16 Gy boost (36) or chemo (BEP ×3).
• Stage IIC / III: Chemo.

Kidney

AJCC 8 — RCC T (size + Gerota line):

• T1a: ≤4 cm, confined to kidney · T1b: >4 to ≤7 cm
• T2a: >7 to ≤10 cm · T2b: >10 cm, confined to kidney
• T3a: Renal vein / segmental branches; perinephric/renal sinus fat (not beyond Gerota)
• T3b: IVC below diaphragm
• T3c: IVC above diaphragm or wall of IVC
• T4: Beyond Gerota's fascia (including ipsilateral adrenal by contiguous extension)

• RCC: SBRT emerging (IROCK pooled) 25–40 / 1–5 for medically inoperable or oligomet.

Penile

AJCC 8 — Penile T:

• Tis: Carcinoma in situ (Bowen, erythroplasia of Queyrat)
• Ta: Non-invasive localized squamous
• T1a: Invades subepithelial CT, no LVI/PNI, not G3–4 (favorable)
• T1b: Subepithelial CT with LVI/PNI or G3–4 (unfavorable)
• T2: Invades corpus spongiosum (± urethra)
• T3: Invades corpus cavernosum (± urethra)
• T4: Adjacent structures (scrotum, prostate, pubic bone)

N (clinical): cN1 palpable mobile unilateral · cN2 palpable mobile multiple/bilateral · cN3 fixed/pelvic.

• Early: organ preservation with brachytherapy (LDR/HDR) or EBRT 65–70. Concurrent chemoRT for advanced.

GU OAR

Prostate: Rectum V50<50, V65<35, V70<20, V75<15 · Bladder V65<50, V80<15 · Femoral heads V50<5% · Penile bulb mean <52 · Small bowel V40<65 cc. SBRT prostate (5-fx): Rectum V36<1 cc, V32<20%; Bladder V37<5 cc; Urethra V42<50%.

7. GYNECOLOGIC (FIGO 2018 cervix; FIGO 2023 endometrium; AJCC version-specific notes)

Cervical (FIGO 2018 major changes: IIIC = nodal)

FIGO 2018 — Cervical cancer (clinicopathologic; imaging and pathology permitted for staging):

• IA: Microscopic only, depth ≤5 mm (horizontal extent no longer used)
• IA1: Depth ≤3 mm · IA2: Depth >3–5 mm
• IB: Clinically visible or microscopic > IA, confined to cervix
• IB1: Depth >5 mm, ≤2 cm greatest dimension
• IB2: >2 to ≤4 cm
• IB3: >4 cm (bulky threshold → definitive chemoRT)
• II: Beyond uterus, not to pelvic wall or lower ⅓ vagina
• IIA: Upper ⅔ vagina, no parametrial (IIA1 ≤4 cm, IIA2 >4 cm)
• IIB: Parametrial involvement, no pelvic wall
• III: Lower ⅓ vagina, pelvic wall, hydronephrosis, or nodes
• IIIA: Lower ⅓ vagina, no pelvic wall
• IIIB: Pelvic wall or hydronephrosis/non-functioning kidney
• IIIC1: Pelvic node metastasis (r=radiologic, p=pathologic)
• IIIC2: Para-aortic node metastasis
• IVA: Bladder/rectal mucosa or beyond true pelvis
• IVB: Distant metastasis

Doses:

• EBRT: 45 / 25 whole pelvis; boost gross nodes to 55–60 (SIB or sequential).
• Brachytherapy (HDR): Point A / HR-CTV total EQD2 80–85 Gy (node-neg), 85–90 (bulky); typical 5.5 × 5 or 6 × 5 HDR fractions. EMBRACE targets: HR-CTV D90 ≥85, bladder D2cc <90, rectum <65–75, sigmoid <70–75.
• Overall treatment time <56 days (critical — prognostic).

Endometrial

FIGO 2009 (still commonly tested — FIGO 2023 added molecular):

• IA: Tumor limited to uterus, <½ myometrial invasion
• IB: ≥½ myometrial invasion
• II: Cervical stromal invasion (endocervical glandular involvement is classified as IA)
• IIIA: Serosa or adnexa
• IIIB: Vaginal or parametrial
• IIIC1: Pelvic nodes
• IIIC2: Para-aortic nodes (± pelvic)
• IVA: Bladder or bowel mucosa
• IVB: Distant metastases (including inguinal nodes, intra-abdominal)

PORTEC-1/2 risk groups:

• Low: IA G1–2, no LVSI → observation
• High-intermediate (HIR): 2 of: age >60, G3, ≥½ invasion, LVSI+ (or stage II) → VBT (PORTEC-2)
• High: IB G3, stage II, serous/clear cell → EBRT ± chemo
• Advanced (III): chemo + RT (PORTEC-3)

FIGO 2009 trial-language: Many landmark endometrial adjuvant trials and older board-style datasets used FIGO 2009, so it remains essential for trial interpretation. FIGO 2023 adds molecular classification and several anatomic/pathologic refinements.

Doses: VBT alone 21 / 3 HDR (7 Gy × 3 to 0.5 cm) or 24 / 3 to surface. Pelvic EBRT 45–50.4 / 25–28. Definitive: 45 EBRT + brachy to EQD2 80+ at Manchester point.

Vulvar

AJCC 8 — Vulvar T:

• T1a: ≤2 cm AND stromal invasion ≤1 mm (DOI) → WLE only, no groin
• T1b: >2 cm OR DOI >1 mm (still confined to vulva/perineum) → needs groin
• T2: Any size with extension to lower ⅓ urethra, lower ⅓ vagina, or anus
• T3: Extension to upper urethra, upper vagina, bladder mucosa, rectal mucosa, or fixed to pelvic bone

N:

• N1a: 1–2 nodes <5 mm · N1b: 1 node ≥5 mm
• N2a: ≥3 nodes <5 mm · N2b: ≥2 nodes ≥5 mm · N2c: Node(s) with ECE
• N3: Fixed or ulcerated nodes

Dose: Adjuvant 50.4 / 28; definitive 60–66; involved groin boost 60.

Vaginal

• Definitive brachytherapy ± EBRT — doses similar to cervix (HR-CTV EQD2 70–80).

Ovarian

• RT rarely used (palliative, dysgerminoma is exception — radiosensitive).

GYN OAR

Bladder V45 <35%, V40 <50% · Rectum V40 <60%, V30 <80% (EMBRACE) · Sigmoid/bowel V40 <250 cc / V30 <500 · Femoral heads V30 <15% · Kidneys (EFRT) mean <18 · Cord 45 · Spinal cord brachy EQD2 <48 · Brachy D2cc: bladder <90, rectum 65–75, sigmoid 70–75, small bowel <70.

8. HEMATOLOGIC / LYMPHOMA (± pediatric & sarcoma high-yield)

Ann Arbor staging (modified by Lugano 2014 for lymphoma — used for both HL and NHL):

• Stage I: Single lymph node region OR single extralymphatic site (IE)
• Stage II: ≥2 nodal regions same side of diaphragm (e.g., II₂ = 2 regions, II₃ = 3); extralymphatic by direct extension = IIE
• Stage III: Nodal regions on both sides of the diaphragm (includes spleen = IIIS)
• Stage IV: Disseminated extralymphatic involvement (diffuse liver, bone marrow, lung nodules not contiguous, CSF/CNS)

Modifiers:

• A: No B symptoms
• B: B symptoms = unexplained fever >38°C, drenching night sweats, weight loss >10% in 6 months
• E: Extranodal extension by direct extension from a nodal site (limited; does NOT apply in stage IV)
• X: Bulky disease — classically >10 cm (GHSG uses ≥5 cm for mediastinal in some protocols) OR mediastinal mass >⅓ maximal thoracic diameter on upright CXR
• S: Splenic involvement (falls into stage III)

Lugano 2014 updates:

• Dropped "X" modifier formally — bulk is recorded by actual size
• Dropped A/B for NHL (retained for HL)
• PET/CT for FDG-avid lymphomas (HL, DLBCL, FL, MCL) replaces BM biopsy in most cases
• Deauville 5-point scale for PET response:
• 1: No uptake · 2: ≤ mediastinum · 3: > mediastinum, ≤ liver
• 4: Moderately > liver · 5: Markedly > liver (2–3× SUVmax) or new sites
• CR: Deauville 1–3 · PR/residual: Deauville 4–5 with interval improvement

Hodgkin Lymphoma

GHSG early-stage risk criteria (know for boards — HD10/HD11/HD14 definitions): A Stage I–II HL patient is "favorable" only if they have NONE of the following: 1. Large mediastinal mass (>⅓ thoracic diameter) 2. Extranodal disease (any E lesion) 3. Elevated ESR (≥50 if no B sx, ≥30 if B sx present) 4. ≥3 nodal areas involved

Any single risk factor → unfavorable (intermediate).

EORTC criteria differ slightly: adds age ≥50 as a risk factor; uses ≥4 nodal areas (not ≥3); mediastinal bulk defined as mediastinal-thoracic ratio >0.35 at T5–6.

NCIC criteria (Meyer trial): histology (mixed cell/LD), age ≥40, ESR ≥50, ≥4 nodal regions.

ISRT concept = involved-site, uses pre-chemo imaging to define CTV with margins (replaces IFRT).

DLBCL / aggressive NHL

Indolent NHL

• Follicular stage I–II: ISRT 24 Gy / 12 fx (FoRT: 24 > 4 Gy, but 4/2 "boom-boom" for palliation/comfort).
• MALT (gastric): Eradicate H. pylori; if persistent → ISRT 24–30 / 12–15.
• Cutaneous (MF/Sezary): TSEBT 12–36 Gy (low-dose 12 Gy effective, repeatable).
• Plasmacytoma: Solitary bone/soft tissue → 45 / 25 (<5 cm) or 50 / 25 (≥5 cm).

Multiple Myeloma

• Palliative: 8 Gy × 1 or 20/5, 30/10. Symptomatic bone lesions, cord compression.

Pediatric lymphomas (see Pediatrics section below for full peds)

• Pediatric HL: Generally treated on COG protocols with response-adapted RT; low-risk often get chemo alone, intermediate/high-risk get 21 Gy IFRT/ISRT to initial sites with slow response or bulk.
• Pediatric NHL (Burkitt, lymphoblastic, DLBCL): Chemo-dominant; RT reserved for CNS+, testicular, or residual disease.

Sarcoma (STS — adult)

Heme/Sarcoma OAR

Heart mean <15 (young HL patients — goal as low as possible) · Lungs V20 <30% · Breasts (young women with mediastinal HL): ALARA · Thyroid: mean <26 (hypothy risk) · Kidneys (para-aortic fields) · Cord 45 · Extremity STS: spare strip of skin/subQ (1.5 cm) to prevent lymphedema; joint range preservation.

9. PEDIATRICS

Note on peds staging: Pediatric tumors use their own disease-specific staging systems — NOT AJCC. Each disease has a unique schema tied to COG/SIOP/EpSSG risk stratification. These systems directly drive both the need for RT and the dose. Peds is heavily tested on the boards — these are the systems you must have cold.

Medulloblastoma

Chang staging system (M-stage drives RT dose for average-risk vs high-risk):

• M0: No evidence of gross subarachnoid or hematogenous metastasis
• M1: Microscopic tumor cells in CSF (positive cytology only)
• M2: Gross nodular seeding in cerebellum/cerebral subarachnoid space or 3rd/4th ventricle
• M3: Gross nodular seeding in spinal subarachnoid space
• M4: Metastasis outside the cerebrospinal axis (bone, bone marrow)

T-stage (Chang, largely historical — not used for risk): T1 <3 cm · T2 ≥3 cm · T3a extension into adjacent structures · T3b brainstem invasion · T4 extension past aqueduct/foramen magnum.

COG risk stratification (average vs high risk): | Risk group | Criteria | |---|---| | Average risk | Age ≥3 years, M0 (no mets), ≤1.5 cm² residual post-op, classic/desmoplastic histology | | High risk | Age <3 (or infant protocols), M+ (M1–M4), >1.5 cm² residual, LC/A (large cell/anaplastic) histology, MYC amplification |

Molecular subgroups (increasingly important): WNT (best prognosis — trials exploring CSI de-escalation to 18 Gy), SHH, Group 3 (worst — MYC amplified), Group 4.

Target: CSI = whole brain + entire thecal sac down to ~S2–S3 (per myelogram/MRI). Boost: whole posterior fossa in older protocols; involved-field tumor bed in contemporary protocols (ACNS0331 showed non-inferiority with reduced boost volume).

Ependymoma

Staging: M0 vs M+ by MRI brain+spine and CSF cytology (all peds brain tumors get this workup).

Age / strategy: Infants and very young children have historically been treated with chemotherapy first to delay RT; ACNS0121 and subsequent pediatric ependymoma protocols support earlier RT in selected young children because local recurrence is the dominant failure pattern.

Low-grade glioma (pediatric)

• Observation after GTR for most WHO Grade 1 (pilocytic astrocytoma).
• Chemotherapy first-line for progressive/unresectable (carbo/vincristine, vinblastine, BRAF/MEK inhibitors for BRAF-altered disease — major shift in past 5 years).
• RT reserved for progression through chemo, typically age ≥10. Dose: 50.4–54 / 28–30 focal.

High-grade glioma & DIPG (pediatric)

• DIPG / H3 K27-altered diffuse midline glioma (WHO Grade 4): Focal RT 54 / 30 is standard of care; provides transient benefit only (median OS ~11 months). Re-irradiation 20–24 Gy on progression is an accepted option (palliative).
• Pediatric HGG: Max resection → RT 54–59.4 with concurrent/adjuvant TMZ (benefit less clear than adult GBM).

Retinoblastoma

International Classification of Retinoblastoma (ICRB) Groups A–E (intraocular):

• A: Small tumors ≤3 mm, away from fovea/disc
• B: Larger or closer to fovea/disc, no seeding
• C: Localized vitreous or subretinal seeding
• D: Diffuse vitreous/subretinal seeding
• E: Extensive tumor filling globe, neovascular glaucoma, anterior chamber involvement, phthisis → typically enucleation

Treatment philosophy: Preserve vision → globe → life (in that order when possible).

• Groups A–B: Focal therapy (laser, cryo, TTT) ± systemic/intra-arterial chemo.
• Groups C–D: Intra-arterial (ophthalmic artery) chemo + focal therapy; plaque brachytherapy (I-125 or Ru-106, 40–45 Gy to tumor apex) for localized failures.
• Group E: Enucleation → adjuvant based on path (PORT if post-laminar optic nerve invasion, scleral invasion, or anterior chamber).
• EBRT (30–45 Gy): Last resort due to second malignancy risk (especially in heritable RB1+ — midface sarcomas). Proton therapy favored when RT is unavoidable.

Wilms tumor (nephroblastoma)

COG staging (post-op, pathology-based; high-yield):

• Stage I: Tumor confined to kidney, completely resected, capsule intact, no biopsy/rupture prior
• Stage II: Extends beyond kidney but completely resected (e.g., penetration of renal capsule, vessel invasion outside kidney parenchyma, biopsy prior to resection — biopsy alone pushes to II)
• Stage III: Residual non-hematogenous tumor confined to abdomen — positive margin, positive abdominal nodes, peritoneal contamination/spillage (any — even local), tumor implants, gross/microscopic residual, or pre-op chemo without complete resection
• Stage IV: Hematogenous metastases (lung, liver, bone, brain) OR lymph node metastases outside abdomen/pelvis
• Stage V: Bilateral renal involvement at diagnosis (each kidney then staged individually)

Histology drives intensity: Favorable histology (FH) vs anaplastic (focal or diffuse) — diffuse anaplasia dramatically worsens prognosis and upgrades intensity.

Whole abdomen RT 10.5 Gy / 7 fx indications: diffuse intraperitoneal spillage, peritoneal implants, pre-op rupture, cytology+ ascites. Boost gross residual to 21.

OAR for Wilms RT: Contralateral kidney should receive <14.4 Gy; liver V20 <50%; whole lung (if WLI) tolerated at 12 Gy but watch for pneumonitis.

Neuroblastoma

INRGSS — International Neuroblastoma Risk Group Staging System (pre-treatment, image-defined risk factors):

• L1: Localized tumor, no image-defined risk factors (IDRFs)
• L2: Locoregional tumor with ≥1 IDRF (IDRFs = encasement of vessels/airways, crossing midline, etc.)
• M: Distant metastatic disease (not MS)
• MS: Metastatic "special" — <18 months old with mets confined to skin, liver, and/or <10% bone marrow (better prognosis, the old "Stage 4S")

COG risk groups (drive treatment intensity): | Risk | Key features | Treatment | |---|---|---| | Low risk | L1 or MS, favorable biology | Surgery alone (± chemo); no RT | | Intermediate risk | L2, favorable biology, <18 mo with unfavorable features | Chemo + surgery; RT only if incomplete response | | High risk | Stage M ≥18 months, or MYCN amplified at any age, or unfavorable histology/ploidy | Induction chemo → surgery → high-dose chemo + ASCT → RT → immunotherapy (dinutuximab) + retinoic acid |

RT for high-risk neuroblastoma:

• Primary tumor bed: 21.6 Gy / 12 fx (after induction + surgery + consolidation)
• Boost to gross residual: +14.4 Gy (total 36) if present
• Metastatic sites (MIBG-avid persistent): 21.6 Gy
• Timed after ASCT, before immunotherapy.

Rhabdomyosarcoma (RMS)

IRS clinical grouping (post-surgical, based on resection extent — drives RT indication and dose):

• Group I: Completely resected, localized, no nodal involvement (I-A confined to site of origin; I-B infiltrating beyond site but resected)
• Group II: Grossly resected but with microscopic residual (II-A), regional node involvement resected (II-B), or both (II-C)
• Group III: Gross residual disease (incomplete resection or biopsy only)
• Group IV: Distant metastases at diagnosis

TNM-based staging (used in combination with Group):

• Stage 1: Favorable site (orbit, non-parameningeal H&N, GU non-bladder/prostate, biliary), any T/N/M0
• Stage 2: Unfavorable site, T1/T2 ≤5 cm, N0
• Stage 3: Unfavorable site, T1/T2 >5 cm OR N1
• Stage 4: M1

COG risk groups combine histology + stage + group: | Risk | Features | |---|---| | Low | Embryonal, Stage 1 Group I–III OR Stage 2 Group I–II | | Intermediate | Embryonal Stage 2–3 Group III / Stage 3 Group I–II, OR alveolar any Stage 1–3 | | High | Any M1 (Stage 4, Group IV) |

Timing: Typically week 13 for Group III (after induction chemo) per ARST protocols.

Ewing sarcoma

Staging: Essentially localized vs metastatic; the key local-control decision is surgery vs RT vs combined, driven by site, resectability, and chemo response.

Target volume: Pre-chemotherapy extent (GTV1) + margin to 45 Gy → post-chemotherapy volume (GTV2) boost to 55.8 (shrinking-field approach; ACNS0621/INT-0091 legacy).

Osteosarcoma

• Primarily surgical disease — RT has a limited role.
• RT for unresectable (axial/skull base/spine osteo): 60–70 Gy, often with protons or carbon ions. SBRT emerging.
• Pulmonary metastasectomy preferred over WLI (unlike Ewing).

Langerhans cell histiocytosis (LCH)

• Low-dose RT (6–10 Gy) for isolated symptomatic bony lesions, especially vertebra plana with cord threat, or refractory to systemic therapy.

CNS prophylaxis in ALL / AML

• CNS-directed therapy historically involved prophylactic CRT; contemporary pediatric ALL regimens rely primarily on intrathecal methotrexate because of neurocognitive late effects.
• Indications for CRT (reserved): CNS3 disease at diagnosis, T-ALL with high WBC (select), relapse.
• Dose: 12–18 Gy prophylactic; 18–24 Gy for overt CNS disease or relapsed disease.
• TBI for HSCT conditioning: 12 Gy / 6 fx BID (fractionated) or 13.2 Gy variants.

Germ cell tumors (pediatric CNS)

Germinoma (WNT-pathway analog of seminoma — exquisitely radiosensitive):

• Localized germinoma: Whole ventricular RT 21–24 Gy + primary boost to 30–40 Gy; chemo has allowed some dose reduction.
• Disseminated germinoma: CSI 24 Gy + primary boost to 40.
• Non-germinomatous GCT (NGGCT): Chemo-intensive + CSI 30.6 + primary boost to 54.

Peds OAR (know the pediatric-specific constraints)

Pediatric tissues are more radiosensitive than adult — these constraints apply across peds sites:

Key principles: 1. Younger = more sensitive — under age 3, RT is generally avoided or deferred with chemo bridging. 2. Protons preferred in peds whenever available, especially for CNS, CSI, skull base, orbit, paraspinal — reduced integral dose → reduced second malignancy and neurocognitive risk. 3. Second malignancy risk is lifetime-cumulative — RT dose and volume should be minimized. 4. Anesthesia is required for daily RT in children typically under age 5–6.

Cross-Cutting Memorization Tables

Classic "single-fraction / short-course" palliative

"Standard" dose-to-know shortlist

Concurrent chemo mainstays

• Cisplatin (weekly 40 or q3wk 100): H&N definitive, NPX, cervix, NSCLC, SCLC (+ etoposide).
• Carbo/paclitaxel: Esophagus CROSS, NSCLC elderly/unfit.
• 5FU/Mitomycin-C: Anal canal, bladder TMT (RTOG 0712).
• 5FU/capecitabine: Rectal, pancreas, gastric.
• TMZ: GBM (concurrent + adjuvant).
• Durvalumab: NSCLC stage III after chemoRT (PACIFIC).

Quick-Reference: Paradigm-Changing Landmarks by Site

• CNS: Age 40, IDH status, MGMT methylation, # brain mets (1–4 vs >10), KPS 70.
• H&N: p16 status, T4a (larynx → surgery), ECE/margin (chemoRT post-op).
• Thoracic: Operability, stage III vs IV, SBRT central vs ultracentral, PACIFIC eligibility (PS 0–1, no progression).
• Breast: Age 50/65/70 cutoffs for boost/omission, node count (≤2 Z0011, ≥4 PMRT), margin.
• GI: Rectal TNT pathway, anal T2 (>4 cm), CROSS eligibility, Child-Pugh for HCC SBRT.
• GU: NCCN risk group, favorable vs unfavorable IR, volume in STAMPEDE M1, ≥pT3/R1 for salvage.
• GYN: FIGO IIIC (node+), HPV status, HR-CTV EQD2 ≥85, overall time <56 days.
• Heme: PET response, bulk ≥10 cm, favorable vs unfavorable HL groups, FLYER eligibility.

Final board-day mental checklist for any case

1. Stage it (applicable AJCC / FIGO system — preserve older trial-era systems when interpreting landmark trials; note exceptions such as HPV-associated OPX, cervix FIGO, endometrial FIGO 2009 vs 2023, Masaoka thymoma, and Ann Arbor for lymphoma).
2. Risk-stratify within stage (prostate NCCN, breast menopausal/node/receptor, glioma molecular).
3. Modality decision: surgery first? definitive RT? chemoRT? trimodality? SBRT eligible?
4. Sequence: neoadjuvant / concurrent / adjuvant / consolidation (PACIFIC, durva).
5. Dose + fractionation with trial name.
6. Target volumes (GTV/CTV/PTV margins, elective nodes — or NOT in NSCLC).
7. OARs — know the 2–3 numbers that matter for that site.
8. Systemic partner (concurrent chemo agent).
9. Follow-up and salvage options.

Memorization aid for board review and trainee education. Cross-check patient-care decisions with NCCN guidelines and site-specific ASTRO clinical practice guidelines. Constraints drawn from QUANTEC, HyTEC, TG-101, and trial protocols.