RANZCR Phase II · Viva Revision Handbook

Rectal Cancer

Clinical decision-making, radiotherapy management and viva-style reasoning for the advanced radiation oncology trainee. Australian (EViQ) practice.

1 Epidemiology & risk

2 Critical anatomy

3 Master flowchart

4 Staging & MRI risk

5 Pathology & molecular

6 Treatment algorithm

7 Total neoadjuvant therapy

8 RT technique & volumes

9 Dose / OAR / EQD2

10 Watch & wait

11 Systemic & immunotherapy

12 Landmark trials

13 Recurrent / metastatic

14 Common viva traps

15 One-page cram sheet

Premium viva revision · minimise prose · think in algorithms Verify all doses against current EViQ before clinical use · June 2026

1

Epidemiology, Aetiology & Presentation

Bowel cancer = 4th most diagnosed cancer (AIHW)
2nd leading cause of cancer death · rectum ≈ ⅓ of CRC

4th

Most diagnosed cancer in Australia

2nd

Leading cause of cancer death (after lung)

~1 in 15

Lifetime risk (M ~1:15, F ~1:16)

~68

Average age at diagnosis (yrs)

Risk factors

Category	Factors
Non-modifiable	Age, male sex, prior CRC/adenoma, prior pelvic RT
Hereditary (~5%)	Lynch / HNPCC (MMR genes, MSI-H), FAP (APC), MUTYH-associated, Peutz-Jeghers, juvenile polyposis
Inflammatory	Ulcerative colitis > Crohn's; risk ∝ duration & extent
Lifestyle	Red/processed meat, low fibre, obesity, physical inactivity, smoking, alcohol, type 2 diabetes

◆Viva pearl — screening (AU)

Australia's National Bowel Cancer Screening Program = biennial iFOBT, lowered to age 45–74 from 1 July 2024 — 45–49s must opt in / request a kit; 50–74s are auto-mailed. Early-onset (<50) incidence is rising. Lynch / FAP need early colonoscopic surveillance and genetics referral.

Presentation & work-up triggers

Rectal bleeding, altered bowel habit, tenesmus, mucus PR
Cramping pain / obstruction (annular tumour)
Iron-deficiency anaemia, weight loss
Often detected via FOBT-positive screening colonoscopy

∴Why rectal ≠ colon

The rectum is extraperitoneal (mid/low), confined by the bony pelvis with a circumferential resection margin at risk and rich lateral lymphatic drainage not removed by standard surgery. This is why local recurrence is the dominant problem and why radiotherapy has a central role it does not have in colon cancer.

Anatomic sub-site (from anal verge, rigid scope)

Third	Distance	Relevance
Lower	0–5 cm	Sphincter / APR risk; W&W candidates
Mid	5–10 cm	Classic TME + neoadjuvant territory
Upper	10–15 cm	Behaves like colon (peritonealised) — often surgery ± chemo, RT frequently omitted

▲Common trap

Don't reflexively offer pelvic RT for an upper-third / rectosigmoid tumour above the peritoneal reflection — it is biologically colon cancer, the CRM is not the issue, and RT often adds toxicity without benefit. Confirm the height and the relationship to the peritoneal reflection on MRI first.

Rectal Cancer · RANZCR Phase II Viva Handbook1 — Epidemiology

2

Critical Surgical & Radiotherapy Anatomy

The mesorectal fascia is the surgical (TME) plane
= the CRM on MRI = the prognostic battleground

Layers, fascia & landmarks

Structure	Significance
Mesorectum	Fatty envelope of lymphovascular tissue & first-echelon nodes around the rectum
Mesorectal fascia (MRF)	Investing fascia = TME dissection plane = CRM on MRI. Tumour ≤1 mm from MRF = involved/threatened
Peritoneal reflection	Anterior ~7–9 cm; divides intraperitoneal (upper) from extraperitoneal (mid/low) rectum
Denonvilliers' fascia	Anterior — recto-vesical (M) / recto-vaginal (F) septum
Waldeyer's (rectosacral)	Posterior — rectum to presacral fascia / sacrum
Anorectal ring / dentate line	Sphincter complex; determines APR vs sphincter-preserving LAR

Lymphatic drainage — why CTV is shaped as it is

Region	Primary drainage	CTV implication
Upper / mid	Superior rectal → IMA / mesorectal	Mesorectum + presacral
Lower	Middle rectal → internal iliac	Add internal iliac ± obturator
Below dentate / anal canal involved	Inferior rectal → inguinal	Add inguinal nodes
Lateral pelvic	Internal iliac, obturator	Not removed by TME → RT / selective lateral node dissection

⌖Blood supply ↔ metastatic pattern

Superior rectal a. (← IMA)
Middle rectal a. (← internal iliac)
Inferior rectal a. (← internal pudendal)

Venous: upper rectum → portal (→ liver mets); mid/low → systemic via internal iliac (→ lung mets, can bypass liver). Explains the differing met patterns of low vs high rectal tumours.

◆Viva pearl — the four MRI questions

For any rectal MRI, answer:

Height — distance of inferior edge from anal verge
mrT stage & depth of extramural spread (T3a–d)
CRM — clear / threatened / involved (≤1 mm)
EMVI & nodal status (mesorectal vs lateral)

These four drive every downstream decision.

∴Why TME revolutionised outcomes

Total mesorectal excision (Heald) removes the rectum + intact mesorectal envelope along the MRF plane, capturing the first nodal echelon en bloc. It dropped local recurrence from ~30% to <10% and reframed RT as an adjunct to optimise the CRM, not a substitute for surgery.

▲Common trap

"Threatened" CRM (tumour/EMVI/node ≤1 mm from MRF) is treated as involved for decision-making — it mandates downstaging neoadjuvant therapy to convert a likely R1 into an R0 resection. Don't wait for frank invasion.

Rectal Cancer · RANZCR Phase II Viva Handbook2 — Anatomy

3

Master Management Flowchart

Biopsy-proven rectal adenocarcinoma → risk-stratified pathway

Biopsy-proven rectal adenocarcinoma

Staging: DRE · rigid sigmoidoscopy · pelvic MRI · CT chest/abdo/pelvis · CEA · colonoscopy

Metastatic (M1)?

Yes — M1

Systemic therapy ± resection of primary/mets · SBRT for oligomets · MDT (see §13)

No — non-metastatic → stratify by MRI

EARLY / GOOD cT1–2 N0 · or cT3a/b N0, MRF clear, EMVI−, upper/mid

→ Upfront TME (LAR/APR).
cT1 favourable → consider local excision.

INTERMEDIATE cT3a/b mid, or cN1–2 with MRF clear, EMVI±, not low

→ TME ± neoadjuvant.
Selected: FOLFOX alone, RT omitted (PROSPECT). Or SCRT → TME.

LOCALLY ADVANCED / UGLY cT3 CRM+/threatened · cT4 · EMVI+ · lateral nodes · low tumour

→ TNT (RAPIDO / PRODIGE-23) → TME.
cCR → consider watch & wait.

∴Why this structure

MRI risk group — not just TNM — drives therapy. The single question is: "can surgery alone achieve a clear CRM and is systemic risk acceptable?" If yes → surgery first. If the CRM is threatened or distant-relapse risk is high → neoadjuvant therapy first, increasingly all systemic + RT before surgery (TNT).

◆Viva pearl — opening move

Always open with "I would confirm histology, assess the patient (PS, comorbidity, continence, DRE), stage with pelvic MRI and CT C/A/P, check CEA, complete the colon, and discuss at MDT." Then commit to a risk group and justify.

Rectal Cancer · RANZCR Phase II Viva Handbook3 — Master flowchart

4

Staging (AJCC 8) & MRI Risk Stratification

TNM defines stage; MRI defines resectability
"Good — Bad — Ugly" (MERCURY)

AJCC / TNM 8th edition

T	Definition
T1	Invades submucosa
T2	Invades muscularis propria
T3	Through MP into perirectal fat a<1 · b1–5 · c5–15 · d>15 mm extramural depth
T4a	Penetrates visceral peritoneum
T4b	Invades adjacent organ/structure

N		M
N1a	1 node	M1a	1 organ
N1b	2–3 nodes	M1b	>1 organ
N1c	Tumour deposit, no node	M1c	Peritoneum
N2a	4–6 nodes
N2b	≥7 nodes

◆Viva pearl

T3 substaging (a–d) matters more than T3 alone: T3a/b (≤5 mm) with clear MRF behaves favourably and may go straight to surgery, whereas T3c/d carries higher relapse risk. EMVI on MRI is an independent predictor of distant relapse.

MRI risk groups — what actually drives treatment

Group	MRI features	Strategy
GOOD	cT1–2 / cT3a–b, N0, MRF clear, EMVI−, not low	Upfront TME (± local excision if cT1)
BAD	cT3a–c any N, or cN+, MRF clear, EMVI±	TME ± SCRT; or FOLFOX±RT-omission (selected)
UGLY	cT3 CRM threatened/involved, cT4, EMVI+, lateral nodes, low	TNT → TME ± organ preservation

The staging investigations & their job

Test	Answers
Pelvic MRI	T, CRM, EMVI, nodes, height — the master tool
Endorectal US	T1 vs T2 in early tumours (if scope passes)
CT C/A/P	Distant metastases
CEA	Baseline / surveillance
Colonoscopy	Synchronous lesions (CT colonography if obstructed)
MMR / MSI	Lynch screen + immunotherapy candidacy

▲Common trap

PET is not routine for primary rectal staging — reserve for equivocal metastatic disease or recurrence work-up.

Rectal Cancer · RANZCR Phase II Viva Handbook4 — Staging

5

Pathology & Molecular Profile

~90% adenocarcinoma NOS · test every tumour for MMR/MSI

Histology & adverse features

Feature	Why it matters
Adenocarcinoma NOS (~90%)	Standard pathway
Mucinous / signet-ring	Often MSI; worse response to chemoRT, poorer prognosis
Poor differentiation (G3)	Adverse; favours systemic intensification
LVI / PNI	Independent adverse prognostic markers
Tumour deposits (N1c)	Upstage; adverse
CRM <1 mm (path)	Strongest predictor of local recurrence
Tumour regression grade	Post-neoadjuvant; mrTRG & path TRG prognostic

⌖Quality metrics to quote

≥12 nodes examined · intact mesorectal specimen (Quirke grading) · R0 with CRM >1 mm · distal margin clear.

Molecular markers & clinical significance

Marker	Significance
MMR / MSI	dMMR/MSI-H → Lynch screen; relative resistance to fluoropyrimidine chemoRT but exquisite immunotherapy sensitivity (see §11)
KRAS / NRAS	Mutation → no benefit from anti-EGFR; guides metastatic therapy
BRAF V600E	Poor prognosis; anti-EGFR resistance; targeted combos
HER2	Emerging target in metastatic disease

◆Viva pearl — dMMR is a game-changer

A dMMR locally advanced rectal cancer should prompt discussion of neoadjuvant immunotherapy (dostarlimab) — early data show very high complete-response and organ-preservation rates. Investigational in Australia (trial-only for rectal, e.g. AZUR-1; PBS-funded only for dMMR endometrial) — consider trial referral. Always check MMR status up front.

∴Why test MMR before chemoRT

dMMR tumours respond poorly to 5-FU-based chemoRT yet may achieve clinical complete response with checkpoint inhibition — identifying them changes the whole pathway, not just adjuvant choice.

Rectal Cancer · RANZCR Phase II Viva Handbook5 — Pathology & molecular

6

Treatment Algorithm by Risk Group

Decision tree — early · intermediate · locally advanced

EARLY — cT1–2 N0

cT1, <3 cm, <⅓ circumf, G1–2, no LVI, sm1?

Yes

Local excision (TEM/TAMIS); adjuvant chemoRT if adverse path

No / cT2

Radical TME (LAR/APR)

∴Why

Local excision spares the morbidity/stoma of TME but only when nodal-risk is <~5%. Adverse path on excision → completion surgery or chemoRT.

INTERMEDIATE — cT3a–c / N+, MRF clear

Needs downstaging / APR-sparing?

Selected

PROSPECT: FOLFOX ×6, RT only if <20% response → TME

Or

SCRT 25/5 or LC-CRT → TME

Adjuvant chemo per path / MDT

∴Why

PROSPECT shows selected intermediate-risk patients can safely omit pelvic RT, sparing late toxicity, when MRF is clear and APR is not required.

LOCALLY ADVANCED — cT3 CRM+ / cT4 / EMVI+ / low

Total Neoadjuvant Therapy

RAPIDO: SCRT→consol chemo
or PRODIGE-23: induction FOLFIRINOX→LC-CRT

Restage — clinical complete response?

cCR

Watch & wait (§10)

Residual

TME

◆Viva pearl — choosing TNT regimen

CRM threatened/T4 (local problem dominant) → favour a schedule with long-course CRT for maximal downstaging (PRODIGE-23 style). High distant-relapse risk → front-load systemic therapy. Either way, delivering all therapy pre-op improves compliance vs post-op chemo.

▲Common trap

Adjuvant chemotherapy evidence after neoadjuvant chemoRT in rectal cancer is weaker than in colon cancer (compliance poor, trials mixed). This is a key driver behind moving all systemic therapy to the neoadjuvant setting (TNT).

Rectal Cancer · RANZCR Phase II Viva Handbook6 — Treatment algorithm

7

Total Neoadjuvant Therapy (TNT)

All chemo + RT before surgery · ↑ pCR · ↓ distant mets
Enables organ preservation

Consolidation model

RAPIDO: SCRT 25/5 → CAPOX/FOLFOX (≈18 wk) → TME

Induction model

PRODIGE-23: FOLFIRINOX ×6 → LC-CRT 50.4/28 + cape → TME → adjuvant

Trial	Design	Key result
RAPIDO	SCRT → consolidation chemo vs standard CRT+surgery+adjuvant	↓ disease-related treatment failure, pCR ~28%, ↓ distant mets (some ↑ local regrowth on longer FU)
PRODIGE-23	Induction FOLFIRINOX → CRT vs CRT alone	↑ 3-yr DFS & metastasis-free survival; pCR ~28%
STELLAR	SCRT → chemo vs CRT	Non-inferior; higher pCR
OPRA	TNT (induction vs consolidation) for organ preservation	Consolidation → higher sustained TME-free survival (~50%)

∴Why TNT works

Moving systemic therapy forward (1) treats micrometastases earlier, (2) achieves far better compliance than post-op chemo, (3) raises pCR rates, opening the door to non-operative organ preservation.

Short-course vs long-course RT

	SCRT 25/5	LC-CRT 50.4/28
Duration	1 week	5–6 weeks + capecitabine
Downstaging	Limited (if immediate surgery)	Substantial
Best for	Resectable, MRF clear; frail; TNT consolidation	CRM threatened / T4 / low needing downstaging
Acute toxicity	Lower (no concurrent chemo)	Higher (GI, skin)

◆Viva pearl

Stockholm III: SCRT with a delay to surgery gives downstaging similar to immediate SCRT-with-shorter-delay and lower toxicity. SCRT + delay (± chemo in the gap) is now an accepted route to downstaging, not just a "fast" option for frail patients.

▲Common trap

SCRT delivered with immediate surgery does little downstaging — if the CRM is involved you need either LC-CRT or SCRT with a deliberate delay ± consolidation chemo. Don't quote "25/5" for a threatened margin without that caveat.

Rectal Cancer · RANZCR Phase II Viva Handbook7 — TNT

8

Radiotherapy Technique & Target Volumes

Simulation → contouring → plan → IGRT delivery

Simulation & set-up

Step	Detail
Position	Supine (standard), comfortably full bladder + empty rectum; knee/ankle immobilisation
Prep	Anal verge marker; IV ± rectal contrast; bladder-filling & bowel protocol
Alternative	Prone on belly board — displaces small bowel (traditional 3DCRT-era; some centres)
Technique	IMRT / VMAT (or 3DCRT) — spares small bowel, bladder, marrow
IGRT	Daily CBCT / kV — bowel & bladder variation

Target volumes (Australian / RTOG consensus)

GTV = primary + involved nodes (MRI/PET fusion)
Elective CTV = mesorectum + presacral space + internal iliac + obturator nodes
Add external iliac if T4 / anterior organ involvement
Add inguinal if lower-third / anal canal involvement
Add ischiorectal fossa if levator/sphincter involved
PTV = CTV + 0.7–1.0 cm (per IGRT)

⌖Dose / fractionation — EViQ SIB (long course)

Volume	Schedule
Elective pelvis (CTV_elective)	45 Gy / 25# (1.8 Gy/#)
Primary + involved nodes (SIB)	50 Gy / 25# (2.0 Gy/#) simultaneous integrated boost
Concurrent chemo	Capecitabine 825 mg/m² BD on RT days (EViQ)
Short course (alternative)	25 Gy / 5# ± delay/consolidation chemo
Re-irradiation	~30–40 Gy hyperfractionated (1.2 Gy BD), individualised

◆Viva pearl — capecitabine & SIB

Capecitabine is the practical radiosensitiser (NSABP R-04: equivalent to infusional 5-FU, avoids a central line). Adding oxaliplatin to chemoRT increases toxicity without survival benefit and is not standard. The SIB delivers elective (45 Gy) and boost (50 Gy) dose in the same 25 fractions — efficient, conformal, and avoids a separate boost phase.

⌖Lateral pelvic nodes

Internal iliac/obturator nodes are not removed by TME. Enlarged lateral nodes → consider a boost to the involved node (e.g. SIB to ~54–55 Gy) or selective lateral node dissection at MDT.

▲Common trap

Avoid treatment gaps and prolonged overall time — they compromise local control. Manage acute skin/GI toxicity proactively to keep the patient on schedule.

Rectal Cancer · RANZCR Phase II Viva Handbook8 — RT technique

9

Dose Summary · OAR Constraints · EQD2

High-yield planning reference

Dose summary table

Indication	Dose / fractionation
Neoadjuvant long-course — elective pelvis	45 Gy / 25#
Neoadjuvant long-course — primary/involved nodes	50 Gy / 25# SIB (EViQ) + capecitabine
Neoadjuvant short-course	25 Gy / 5#
Bulky/lateral node — higher SIB (selected)	≈54–55 Gy / 25#
Definitive (inoperable) ± boost	50–54 Gy/25–28# ± contact/EBRT boost
Palliative	30 Gy/10#, 25 Gy/5#, or 5 Gy×5

OAR constraints (pelvic EBRT)

Organ	Constraint
Small bowel	V45 < 195 cc; V15 < 830 cc; minimise loops in PTV
Bladder	V45 < 50–60%; Dmax < ~50 Gy
Femoral heads	V45 < 25–40%; Dmax < 50 Gy
Genitalia / perineum	Minimise — skin toxicity
Pelvic bone marrow	V40 < 37% (relevant with concurrent chemo)

Biological equivalence — short vs long course

Schedule	Tumour EQD2₁₀	Late EQD2₃
25 Gy / 5#	≈ 31 Gy	≈ 40 Gy
45 Gy / 25# (1.8 Gy)	≈ 44 Gy	≈ 43 Gy
50 Gy / 25# SIB (2.0 Gy)	≈ 50 Gy	≈ 50 Gy

α/β = 10 (tumour/acute), 3 (late). Note SCRT delivers a higher late-effect dose per fraction — relevant to re-irradiation tolerance and to why immediate-surgery SCRT downstages less.

∴Why an SIB (not a separate boost phase)

The pelvis carries micrometastatic risk and is dose-limited by small bowel, so the elective volume gets 45 Gy while only the gross disease is simultaneously lifted to 50 Gy within the same 25 fractions. This shortens overall treatment time and improves conformality versus a sequential boost. Dose-escalation beyond this (e.g. contact brachytherapy boost) is explored for organ preservation, not routine resectable disease.

◆Viva pearl

Quote constraints as principles ("keep small-bowel V45 down, respect bladder and femoral heads, watch marrow with concurrent chemo") rather than memorised decimals — examiners want to see you understand the dose-limiting organs.

Rectal Cancer · RANZCR Phase II Viva Handbook9 — Dose / OAR / EQD2

10

Organ Preservation — Watch & Wait

cCR after TNT → non-operative management
cCR ≠ pCR · regrowth ~25–30%, mostly salvageable

Confirming clinical complete response (cCR)

Modality	cCR appearance
DRE	No palpable tumour, no mass/ulcer
Endoscopy	Flat white scar, telangiectasia; no ulcer/nodularity
MRI (incl. DWI)	mrTRG 1–2, no residual tumour signal, no suspicious node

Surveillance schedule

DRE + endoscopy every 3 months for 1–2 yrs, then less often
Pelvic MRI regularly; serial CEA
CT chest/abdomen for distant disease
Regrowth → salvage TME with curative intent

⌖Evidence base

Habr-Gama (pioneer cohorts) · OPRA (consolidation arm ~50% organ preservation) · International Watch & Wait Database (IWWD) — regrowth ~25%, >95% in first 2 yrs, most salvageable; survival comparable when surveillance rigorous.

◆Viva pearl — counselling

Be explicit: radiological/clinical CR is not pathological CR. W&W trades the morbidity and stoma risk of TME for a lifelong commitment to intensive surveillance and acceptance of a ~25–30% regrowth risk. It suits a motivated, reliable patient who can attend frequent follow-up.

∴Why consolidation beats induction here

OPRA showed consolidation chemo (chemo after CRT) gave higher sustained organ preservation than induction — the longer interval from RT to assessment allows maximal tumour regression before the response is judged.

▲Common trap

Don't biopsy a cCR scar routinely — a negative superficial biopsy doesn't exclude deep residual disease and risks poor healing. Judge response on the triad (DRE + endoscopy + MRI), not biopsy.

▲Common trap

Surveillance must be more intensive than for resected patients — regrowth is salvageable only if caught early. A patient who can't commit to this is not a W&W candidate.

Rectal Cancer · RANZCR Phase II Viva Handbook10 — Watch & wait

11

Systemic Therapy & Immunotherapy

Fluoropyrimidine backbone · TNT chemo · dMMR immunotherapy

Chemotherapy regimens

Setting	Regimen
Concurrent (radiosensitiser)	Capecitabine 825 mg/m² BD on RT days (or infusional 5-FU)
TNT — consolidation/induction	CAPOX or FOLFOX; PRODIGE-23 used FOLFIRINOX induction
Adjuvant (selected)	FOLFOX / CAPOX — weaker evidence than colon; per path & MDT
Metastatic	FOLFOX/FOLFIRI ± bevacizumab; anti-EGFR if RAS/BRAF WT & left-sided

∴Why fluoropyrimidine concurrent

5-FU/capecitabine radiosensitises and improves local control & pCR; oxaliplatin concurrently adds toxicity without benefit (ACCORD-12, STAR-01) — reserve oxaliplatin for the systemic (induction/consolidation) phase.

Immunotherapy — dMMR / MSI-H

Scenario	Therapy	AU access
Metastatic dMMR	Pembrolizumab 1st-line (KEYNOTE-177)	PBS-listed (Aug 2021)
Metastatic pMMR	Chemo ± biologics (bevacizumab; anti-EGFR if RAS/BRAF WT & left-sided)	PBS per criteria
Neoadjuvant dostarlimab (LA rectal, dMMR)	Cercek cohort / AZUR-1 — very high cCR, organ preservation without RT/surgery	Trial only — not TGA/PBS approved for rectal

◆Viva pearl

The dostarlimab data (100% cCR in dMMR rectal cohorts; Cercek & AZUR-1 phase II registrational study, AACR 2025) is among the most striking in oncology — flag it as practice-evolving. In Australia it is investigational / trial-only for rectal (AZUR-1 — phase II monotherapy, dMMR LA rectal; cf. AZUR-2 — phase III perioperative dostarlimab in dMMR colon), and dostarlimab is TGA/PBS-approved here only for dMMR endometrial. With Breakthrough Therapy designation it is likely to reach the PBS for rectal in the near future. Check MMR on every rectal cancer up front and consider trial referral.

▲Common trap

dMMR tumours respond poorly to fluoropyrimidine chemoRT — recognising dMMR flags immunotherapy as the evolving direction (and trial eligibility) rather than a reason to intensify chemoRT.

Rectal Cancer · RANZCR Phase II Viva Handbook11 — Systemic & immunotherapy

12

Landmark Trials

Who · broad result · why we still care (viva level)

Trial	Cohort	Main result	Practice-changing message
German CAO/ARO/AIO-94 (Sauer)	cT3–4 / N+ rectal; pre- vs post-op CRT	Pre-op ↓ local recurrence, ↓ toxicity, ↑ sphincter preservation	Established neoadjuvant chemoRT as standard
Dutch TME	Resectable rectal; SCRT + TME vs TME	SCRT halved local recurrence	RT adds to good surgery; TME is the surgical standard
MRC CR07	SCRT vs selective post-op CRT	SCRT superior local control	Pre-op > selective post-op approach
Stockholm III	SCRT timing / delay to surgery	SCRT + delay = downstaging, ↓ toxicity	Legitimised SCRT with delay as a downstaging route
RAPIDO	High-risk; SCRT→consolidation chemo (TNT)	↓ treatment failure, ↑ pCR, ↓ distant mets	Validated TNT; front-load systemic therapy
PRODIGE-23	cT3–4; induction FOLFIRINOX→CRT (TNT)	↑ DFS & metastasis-free survival	Induction-chemo TNT improves distant control
OPRA	TNT for organ preservation	~50% organ preservation; consolidation > induction	Framework for non-operative management
PROSPECT	Intermediate-risk; FOLFOX ± selective RT	Non-inferior DFS; RT omitted in most	RT can be safely omitted in selected patients
Cercek / AZUR-1 (dostarlimab)	dMMR locally advanced rectal	Striking cCR; organ preservation without RT/surgery	Immunotherapy practice-evolving in dMMR — trial-only in AU (AZUR-1; not yet PBS for rectal)

◆Viva pearl — the narrative arc

Tell the story, don't list numbers: TME fixed surgery → neoadjuvant RT (German trial) cut local recurrence → TNT (RAPIDO/PRODIGE-23) front-loaded systemic therapy and raised pCR → that pCR enabled organ preservation (OPRA) → and we now de-escalate by omitting RT (PROSPECT) or using immunotherapy in dMMR. The field is moving from "more therapy for all" to "the right therapy for each."

Rectal Cancer · RANZCR Phase II Viva Handbook12 — Landmark trials

13

Recurrent & Metastatic Disease

Short version — pattern dictates strategy

Recurrence / metastatic — restage (MRI, CT, PET, CEA), MDT

Local / pelvic

RT-naïve → CRT then surgery.
Prior RT → re-irradiation (hyperfx 1.2 Gy BD) ± surgery; exenteration in fit, resectable

Oligometastatic

Metastasectomy (liver/lung) ± peri-op chemo; SBRT to oligomets

Disseminated

Palliative systemic therapy; dMMR → checkpoint inhibitor; palliative RT for bleeding/pain/obstruction

Pattern	Key options
Isolated pelvic, RT-naïve	Long-course CRT → surgical resection (curative intent)
Pelvic, previously irradiated	Re-RT (≈30–40 Gy, 1.2 Gy BD) ± surgery / exenteration; IORT in selected centres
Liver/lung oligomets	Resection / SBRT ± systemic therapy
Widespread	Palliative chemo ± biologics; IO if dMMR; symptom-directed RT

◆Viva pearl — re-irradiation

Pelvic re-RT uses hyperfractionation (1.2 Gy BD) to respect previously-irradiated late-responding tissue; quote cumulative bowel/bladder tolerance and emphasise MDT + careful informed consent regarding fistula/toxicity risk.

⌖Palliative menu

30 Gy/10#, 25 Gy/5#, or 5 Gy×5 (then optional further) for bleeding, pain or obstruction — choose by prognosis and fitness.

▲Common trap

An oligometastatic dMMR patient may be better served by immunotherapy than aggressive local ablation alone — always check MMR status before committing to a purely local strategy.

Rectal Cancer · RANZCR Phase II Viva Handbook13 — Recurrent / metastatic

14

Common Viva Traps

The mistakes examiners are listening for

▲Upper rectum ≠ mid/low rectum

Upper-third / rectosigmoid tumours are intraperitoneal — treat like colon (surgery ± chemo); RT often unnecessary.

▲Threatened CRM = involved

Tumour/EMVI/node ≤1 mm from MRF mandates downstaging neoadjuvant therapy — don't wait for frank invasion.

▲SCRT ≠ downstaging if immediate surgery

For a threatened margin use LC-CRT, or SCRT with deliberate delay ± consolidation chemo.

▲RT is not always required

PROSPECT: selected intermediate-risk (MRF clear, no APR needed) can have FOLFOX alone, omitting pelvic RT.

▲Concurrent oxaliplatin adds toxicity, not benefit

Keep oxaliplatin for the systemic phase; capecitabine/5-FU is the concurrent radiosensitiser.

▲cCR ≠ pCR

Watch & wait carries ~25–30% regrowth; only safe with intensive, reliable surveillance.

▲Don't biopsy the cCR scar routinely

Negative superficial biopsy doesn't exclude deep residual; judge on DRE + endoscopy + MRI triad.

▲Adjuvant chemo evidence is weaker in rectal

Compliance is poor post-op — a key reason to deliver systemic therapy as TNT.

▲Lateral pelvic nodes escape TME

Internal iliac/obturator nodes need RT boost or selective dissection — surgery alone misses them.

▲Always check MMR status

dMMR redirects management toward immunotherapy and away from intensified chemoRT.

▲EMVI is independently prognostic

EMVI+ predicts distant relapse and pushes toward TNT even with otherwise "intermediate" features.

▲Don't forget the patient

Continence, sphincter function, stoma acceptance and fitness shape the choice between LAR, APR and organ preservation as much as the stage does.

Rectal Cancer · RANZCR Phase II Viva Handbook14 — Common traps

15

One-Page Cram Sheet

2-minute pre-viva review · tables only

MRI — the 4 questions

1	Height from anal verge
2	mrT + extramural depth (T3a–d)
3	CRM: clear / threatened / involved (≤1 mm)
4	EMVI + nodes (mesorectal vs lateral)

Risk → strategy

GOOD	cT1–2/T3a-b N0, MRF clear → TME
BAD	cT3/N+, MRF clear → TME ± SCRT / FOLFOX (PROSPECT)
UGLY	CRM+/T4/EMVI+/low → TNT → TME ± W&W

Key doses (EViQ)

LC elective	45 Gy/25#
SIB primary/nodes	50 Gy/25# + capecitabine 825 BD
Short course	25 Gy/5#
Palliative	30/10, 25/5, 5×5

TNT regimens

RAPIDO	SCRT 25/5 → consolidation CAPOX/FOLFOX → TME
PRODIGE-23	Induction FOLFIRINOX → LC-CRT → TME → adjuvant
OPRA	Consolidation > induction for organ preservation (~50%)

Systemic / immuno

Concurrent	Capecitabine 825 mg/m² BD (no concurrent oxali)
dMMR LA rectal	Dostarlimab — trial only (AZUR-1)
Metastatic dMMR	Pembrolizumab 1st-line (PBS)

OAR (principles)

Small bowel	V45 < 195 cc — the dose-limiter
Bladder	V45 < 50–60%
Femoral heads / marrow	Respect with concurrent chemo

Watch & wait

cCR triad	DRE + endoscopy (white scar) + MRI (mrTRG1–2)
Regrowth	~25–30%, >95% <2 yr → salvage TME
Caveat	cCR ≠ pCR; needs intensive surveillance

Trial one-liners

German (Sauer)	Pre-op > post-op CRT
Dutch TME / CR07	SCRT ↓ local recurrence
RAPIDO / PRODIGE-23	TNT ↑ pCR, ↓ distant mets
PROSPECT	Omit RT in selected
Cercek	dMMR → IO, organ preservation

▲Top traps

Upper rectum = colon · threatened CRM = involved · check MMR · RT omissible (PROSPECT) · cCR ≠ pCR · lateral nodes escape TME.

Low/good risk Intermediate High-intermediate High / locally advanced Viva pearl Common trap Why box Planning

Rectal Cancer · RANZCR Phase II Viva Handbook · verify doses against EViQ15 — Cram sheet