Surgical Insight Hub Monograph
Colorectal & Anal Surgery
Comprehensive Exam Notebook
ABSITE · MRCS · FRCS Board Review
Table of Contents
- Benign Colorectal Tumors — Polyps, FAP, Lynch Syndrome
- Operative atlas · Paris/Haggitt/Kikuchi classification · Polyposis syndromes table · Lynch testing algorithm · Surveillance intervals · Viva scenarios
- Colon Cancer (CRC)
- CME/D3 anatomy · TNM 8th Ed staging · Molecular profiling · Adjuvant chemotherapy by stage · IDEA/KEYNOTE-177/BEACON trials · Viva scenarios
- Rectal Cancer
- TME holy plane · CRM/EMVI · Risk stratification · RAPIDO/PRODIGE 23/OPRA trials · Watch-and-Wait criteria · LPND debate · Viva scenarios
- Colorectal Liver Metastases & Peritoneal Disease
- Resectability criteria · FLR calculation · EORTC 40983 · PRODIGE 7/HIPEC · CRS/PCI · HAI pump · Viva scenarios
- Anal Canal Tumors
- Anatomy/lymphatics · Anal SCC/Nigro protocol · AIN/HSIL · Anorectal melanoma · ACT II/ACCORD-03/ANCHOR trials · Viva scenarios
- Fournier's Gangrene
- Fascial planes · Debridement steps · Microbiology · FGSI scoring · Antibiotic protocol · ICU management · Visualizations
- Master Exam Summary Table
Monograph 1 of 6
Benign Colorectal Tumors
Polyps · Polyposis Syndromes · Lynch Syndrome
Section 1 — Operative Atlas
Endoscopic Resection Techniques
| Technique | Indication | Key Technical Points |
|---|---|---|
| Cold snare polypectomy (CSP) | Polyps ≤10 mm | No submucosal injection; en bloc preferred |
| Hot snare polypectomy | 10–20 mm pedunculated | Coagulation current; Endoloop for thick stalks >10 mm |
| EMR | Flat/sessile 10–20 mm | Submucosal lift saline + methylene blue; piecemeal acceptable |
| ESD | >20 mm, scarred, LST-NG | En bloc; higher perforation risk; expert centres only |
| TAMIS/TEM | T1 rectal cancer ≤3 cm, uN0 | Full-thickness excision; 1 cm margin; close defect |
Malignant Polyp — Decision
Adverse features mandating surgery: Haggitt level 4 · Kikuchi Sm3 · lymphovascular invasion · poor differentiation · margin <1 mm
No adverse features + clear margin: Surveillance colonoscopy at 3 months — no surgery required
Surgical Resection — When Endoscopy Fails
- Laparoscopic right hemicolectomy: ileocolic, right colic, right middle colic divided; CME with D3 for malignant polyps
- Proctocolectomy + IPAA (J-pouch): definitive FAP operation age 15–25; staged 2 or 3-step
- IRA (ileorectal anastomosis): AFAP with <20 rectal polyps; lifelong rectal surveillance q6–12 months
- Subtotal colectomy: Lynch syndrome with synchronous lesions or young patient
Section 2 — Classifications & Pathology
Paris Classification
| Class | Description | Malignant Risk |
|---|---|---|
| Ip | Pedunculated | Low–moderate |
| Is | Sessile | Moderate |
| IIa | Superficial elevated | Low |
| IIb | Flat | Moderate |
| IIc | Depressed | High |
| IIa+IIc | Mixed | High |
| III | Excavated/ulcerated | Very high |
Histological Subtypes
| Type | Villous % | Malignant Risk |
|---|---|---|
| Tubular adenoma | <25% | ~5% |
| Tubulovillous | 25–75% | ~20% |
| Villous adenoma | >75% | ~40% |
| SSL (sessile serrated lesion) | None (serrated crypts) | Via BRAF/MLH1 methylation |
| TSA (traditional serrated) | Serrated + dysplasia | Intermediate |
Haggitt & Kikuchi Classifications
| System | Levels | Exam Rule |
|---|---|---|
| Haggitt (pedunculated T1) | 1: head · 2: neck · 3: stalk · 4: into bowel wall submucosa | Level 4 = surgery |
| Kikuchi (sessile T1) | Sm1 <1/3 · Sm2 mid · Sm3 >2/3 submucosa | Sm3 = surgery; Sm1 + clear margin = surveillance |
Molecular Pathways
| Pathway | Key Mutation | Polyp Type | Syndrome | CRC Features |
|---|---|---|---|---|
| CIN | APC → KRAS → TP53 | Tubular/villous adenoma | FAP, sporadic | MSS, left-sided |
| dMMR | MLH1, MSH2, MSH6, PMS2 | Flat, right-sided | Lynch | MSI-H, mucinous, right-sided |
| Serrated | BRAF V600E + MLH1 methylation | SSL/HP | Sporadic serrated | MSI-H or MSS |
| MUTYH | MUTYH (biallelic) | Multiple adenomas | MAP | G:C→T:A transversion |
Polyposis Syndromes Master Table
| Syndrome | Gene | Inheritance | Cancer Risk | Extraintestinal | Surgery |
|---|---|---|---|---|---|
| FAP | APC (5q21) | AD | ~100% CRC by 40 | CHRPE, desmoid, osteoma, thyroid | Proctocolectomy + IPAA age 15–25 |
| AFAP | APC (5'/3' end) | AD | ~70% CRC | Fewer extracolonic | IRA if <20 rectal polyps; else IPAA |
| Gardner | APC | AD | Same as FAP | Epidermoid cysts, desmoids, osteomas | Same as FAP |
| Turcot | APC or MMR | AD | High | CNS tumours (medulloblastoma/glioblastoma) | Context-dependent |
| MAP | MUTYH (biallelic) | AR | ~80% CRC | Sebaceous lesions, duodenal polyps | Surveillance; surgery when unmanageable |
| PJS | STK11/LKB1 | AD | 39% CRC; 36% breast; 13% gastric | Mucocutaneous melanosis, sex cord tumours | Baseline scope age 8; MR enterography |
| JPS | SMAD4/BMPR1A | AD | 39–68% GI cancer | SMAD4: HHT features | Colectomy when >5 polyps/HGD |
| Cowden/PHTS | PTEN | AD | Moderate CRC | Macrocephaly, thyroid/breast/endometrial Ca | Annual surveillance |
Lynch Syndrome — Exam Essentials
Amsterdam II (3-2-1 rule): ≥3 relatives with Lynch-associated cancer · ≥2 generations · ≥1 diagnosed <50 years · FAP excluded · pathologically confirmed
| Gene | CRC Lifetime Risk | Associated Extra-Colonic Cancers |
|---|---|---|
| MLH1 | 40–80% | Endometrial 40–60%, ovary, stomach, urinary tract |
| MSH2 | 40–80% | Endometrial, ovary, urinary tract, sebaceous (Muir-Torre) |
| MSH6 | 10–22% | Endometrial predominant |
| PMS2 | 15–20% | Lower penetrance |
| EPCAM | MSH2 silencing | Urinary tract prominent |
Surveillance Intervals — MSTF 2020 / BSG 2020
| Finding | Next Colonoscopy |
|---|---|
| 1–2 tubular adenomas <10 mm, LGD | 7–10 years |
| 3–4 adenomas OR any 10–19 mm OR any HGD | 3 years |
| ≥5 adenomas OR any ≥20 mm | 1 year |
| SSL <10 mm, no dysplasia | 5 years |
| SSL ≥10 mm OR SSL with dysplasia | 1 year |
| Piecemeal resection ≥20 mm | 3–6 months (scar check) |
| FAP post-IRA (rectal remnant) | Every 6–12 months |
| Lynch syndrome | Annual from age 25 (or 5 yrs before youngest affected relative) |
Section 3 — Board Review / Viva
Q1. T1 adenocarcinoma, Kikuchi Sm2, moderate differentiation, no LVI, margin 1.5 mm. Operate or surveil?
A: Low-risk T1 — Sm2 with clear margin (>1 mm), no LVI, moderate differentiation. ESGE/BSG support surveillance: colonoscopy at 3 months, then 1 year.
Q2. 16-year-old, APC mutation, 200+ adenomas, 12 rectal polyps. What operation?
A: Proctocolectomy + IPAA. IRA acceptable only if <20 rectal polyps and patient strongly prefers; requires 6-monthly flexible sigmoidoscopy for life. IPAA is oncologically superior here.
Q3. 22-year-old FAP patient develops 8 cm intra-abdominal mass. No CRC. Diagnosis and management?
A: Desmoid tumour (mesenteric fibromatosis) — leading cause of death in FAP post-colectomy. Treat with sulindac + tamoxifen first-line; imatinib/sorafenib for progression. Avoid surgery unless obstruction/life-threatening — trauma triggers growth.
Q4. 35 adenomas, APC negative. Next test?
A: MUTYH-associated polyposis (MAP). Test biallelic MUTYH mutation. Autosomal recessive. CRC lifetime risk ~80%.
Q5. MSI-H Stage II T2N0M0 sigmoid cancer. Adjuvant chemotherapy?
A: No adjuvant therapy. MSI-H Stage II has favourable prognosis; 5-FU is potentially harmful in dMMR tumours. Pembrolizumab not approved in adjuvant Stage II setting.
CAPP2 trial (Burn, Lancet 2011): Aspirin 600 mg/day significantly reduced Lynch-associated CRC (HR 0.63) after 4+ years. CAPP3 evaluating optimal dose (100 vs 300 vs 600 mg).
Section 4 — Visualization
CRC Molecular Pathways & Lynch Tumour Testing Algorithm
Monograph 2 of 6
Colon Cancer (CRC)
Right-sided · Left-sided · Sigmoid · CME/D3 · Adjuvant Therapy
Section 1 — Operative Atlas
Key Anatomical Landmarks
- Toldt's fascia: embryological fusion plane — the correct CME dissection plane; avascular, preserves ureter and gonadal vessels
- Right ureter: crosses right iliac vessels at pelvic brim, lateral to ileocolic pedicle; lift mesentery medially to identify
- SMV: medial landmark for right hemicolectomy; ileocolic vein defines vascular pedicle
- Left ureter: posterior to IMA origin — always identify before IMA ligation
- IMV: ligated at inferior pancreatic border in left hemicolectomy for tension-free anastomosis
- Hypogastric nerves: arise at IMA origin; injured during high IMA ligation if dissection goes posterior to pre-aortic fascia → ejaculatory dysfunction
CME principle (Hohenberger 2009): Sharp dissection in embryological fascial planes + central vascular ligation at mesenteric root (D3) + intact mesocolic envelope. RELARC trial 2024 confirmed DFS benefit of CME vs D2.
Section 2 — TNM Staging & Molecular Profiling
TNM 8th Edition — Colon Cancer
| T Stage | Definition | N Stage | Definition |
|---|---|---|---|
| Tis | Carcinoma in situ (intramucosal) | N0 | No regional nodes |
| T1 | Into submucosa | N1a | 1 positive node |
| T2 | Into muscularis propria | N1b | 2–3 positive nodes |
| T3 | Through MP into pericolorectal tissue | N1c | Tumour deposit(s), no positive node |
| T4a | Penetrates visceral peritoneum | N2a | 4–6 positive nodes |
| T4b | Invades/adheres to adjacent organ | N2b | ≥7 positive nodes |
AJCC Stage Grouping & Survival
| Stage | TNM | 5-Year Survival |
|---|---|---|
| I | T1–2 N0 M0 | ~92% |
| IIA | T3 N0 M0 | ~87% |
| IIB | T4a N0 M0 | ~65% |
| IIC | T4b N0 M0 | ~58% |
| IIIA | T1–2 N1 / T1 N2a | ~90% |
| IIIB | T3–4a N1 / T2–3 N2a / T1–2 N2b | ~72% |
| IIIC | T4a N2a / T3–4a N2b / T4b N1–2 | ~53% |
| IV | Any T, any N, M1 | ~14% |
High-risk Stage II features (adjuvant chemo indicated): T4 · bowel obstruction/perforation · <12 nodes examined · LVI/PNI · poor differentiation · positive margins
MSI-H Stage II exam trap: Do NOT give 5-FU monotherapy — may be harmful in dMMR tumours
Molecular Profiling
| Biomarker | Clinical Impact |
|---|---|
| RAS (KRAS/NRAS) mutant | Anti-EGFR (cetuximab/panitumumab) CONTRAINDICATED |
| BRAF V600E | Poor prognosis; BEACON triplet (encorafenib + binimetinib + cetuximab) for metastatic |
| MSI-H/dMMR | Stage II: avoid 5-FU alone; metastatic: pembrolizumab 1st line (KEYNOTE-177) |
| HER2 amplified | RAS/BRAF WT: trastuzumab + pertuzumab (MOUNTAINEER) |
| NTRK fusion | Larotrectinib/entrectinib regardless of histology |
Adjuvant Chemotherapy by Stage
| Stage | Regimen | Key Trial |
|---|---|---|
| Stage I | No adjuvant | Surgery curative |
| Stage II low-risk | No adjuvant (or discuss) | No RCT benefit |
| Stage II high-risk | CAPOX × 3 months (preferred) | IDEA collaboration |
| Stage III low-risk (T1–3, N1) | CAPOX × 3 months | IDEA: 3-month CAPOX non-inferior |
| Stage III high-risk (T4 or N2) | FOLFOX × 6 months | IDEA: 6 months superior |
| Metastatic 1st line | FOLFOX + bevacizumab / FOLFIRI + bev | TREE, FOLFOX4 vs IFL |
| Metastatic MSI-H | Pembrolizumab (KEYNOTE-177) | PFS HR 0.60; OS benefit confirmed |
| Metastatic BRAF V600E | BEACON triplet | ORR 26%; OS 9.0 vs 5.4 months |
EPOC trial exam trap: FOLFOX + cetuximab perioperatively in RAS WT CRLM — cetuximab WORSENED outcomes. Never give anti-EGFR perioperatively.
Section 3 — Board Review / Viva
Q1. Right-sided obstructing CRC, no perforation, no metastases. Management?
A: Right-sided obstruction — primary resection and anastomosis safe. Laparoscopic right hemicolectomy. No role for SEMS right of hepatic flexure (technically difficult, high perforation risk).
Q2. T3N1a MSS, KRAS mutant, CEA normalised. Adjuvant therapy?
A: Stage IIIA. FOLFOX × 6 months or CAPOX × 3–6 months. MSS excludes pembrolizumab. KRAS excludes anti-EGFR. Adjuvant bevacizumab not proven (AVANT, QUASAR 2 — negative).
Q3. Post-op day 4 fever + abdominal pain after left hemicolectomy. CT shows pneumoperitoneum. Clavien-Dindo grade?
A: Anastomotic leak requiring laparotomy = Clavien-Dindo IIIb.
Section 4 — ERAS 2025 Protocol
| Phase | Key Interventions |
|---|---|
| Pre-op | MBP + oral antibiotics (metronidazole + neomycin) · carbohydrate loading 2 hrs pre-op · IV iron if Hb <110 g/L with iron deficiency · LMWH 12 hrs pre-op |
| Intra-op | Laparoscopic default · GDFT (oesophageal Doppler/LiDCO) · no routine NGT · TAP block + intrathecal morphine · cefuroxime + metronidazole at induction |
| Post-op D0 | Oral fluids 4 hrs post-op · mobilise same day · catheter removal at 24 hrs |
| Post-op D1–2 | Low-residue diet · stop IV fluids when tolerating orally · paracetamol + NSAIDs + PRN opioid · chewing gum · laxatives |
| Discharge | Tolerating diet · pain VAS <3 · passing flatus · independent mobility · LOS: lap right hemi 2–3 days; proctocolectomy 4–5 days |
Monograph 3 of 6
Rectal Cancer
TME · Neoadjuvant Therapy · Watch-and-Wait · LPND
Section 1 — Operative Atlas
The TME Plane — Key Anatomical Points
| Structure | Definition | Surgical Significance |
|---|---|---|
| Holy plane (Heald) | Areolar tissue between visceral mesorectal fascia and parietal sacral fascia | Avascular; preserves autonomic nerves; complete mesorectal excision |
| Waldeyer's fascia | Presacral fascia thickening at S4 | Must be divided sharply at S4–5 to complete posterior dissection |
| Denonvilliers' fascia | Between posterior prostate/seminal vesicles and anterior mesorectum | For anterior T3+ tumours: dissect anterior to this fascia for R0 CRM |
| Hypogastric nerves | Paired nerves lateral to mesorectum at sacral promontory | Injury → retrograde ejaculation; stay medial in holy plane |
| Pelvic nerves (S2–4) | Parasympathetics joining pelvic plexus lateral to mid-low rectum | Injury → erectile dysfunction + bladder dysfunction; at risk during lateral dissection |
| CRM | Tumour ≤1 mm from cut lateral surface of TME specimen | CRM+ = independent predictor of local recurrence (HR 3.5) and OS |
CRM threatened on MRI = tumour signal ≤1 mm from mesorectal fascia → neoadjuvant mandatory
Operative Approaches
| Approach | Indication | Key Points |
|---|---|---|
| Laparoscopic TME (LAR) | Upper/mid rectum, T1–3 | 5-port; medial-to-lateral; mandatory splenic flexure mobilisation |
| Robotic TME | Mid/low rectum, narrow pelvis | ROLARR: no difference in CRM+ vs laparoscopic |
| TaTME | Low rectum, high BMI, narrow pelvis | Simultaneous transabdominal + transanal dissection |
| ELAPE/Cylindrical APR | Ultra-low tumour, sphincter involved | Reduces CRM+ from ~30% (standard APR) to ~10%; prone perineal phase |
| ISR (intersphincteric resection) | T1–2, 1–3 cm from dentate, good sphincter | Pre-op anorectal manometry; risk of major LARS |
Section 2 — Risk Stratification & Neoadjuvant Therapy
MRI Staging Parameters
| Parameter | Definition | Clinical Impact |
|---|---|---|
| CRM | Tumour ≤1 mm from mesorectal fascia | CRM+ → neoadjuvant mandatory |
| EMVI | Tumour in extramural veins | Systemic recurrence risk; worse OS |
| T3 subclassification | T3a <1mm · T3b 1–5mm · T3c 5–15mm · T3d >15mm | T3c/d = high-risk; neoadjuvant considered |
| TRG (Mandard) | 1 = complete response · 5 = no response | TRG 1–2 = consider watch-and-wait |
| Lateral pelvic nodes | Internal iliac/obturator territory | ≥7mm pre-CRT or ≥4mm post-CRT = positive |
ESMO Risk Stratification & Treatment
| Risk Group | MRI Features | Treatment |
|---|---|---|
| Very low / low | T1–2 N0, CRM clear | Primary surgery |
| Intermediate | T3c/d, N1–2, CRM clear | SCRT + CAPOX (RAPIDO) or LCRT |
| High / LARC | Threatened CRM, T4, LPN+ | LCRT + induction FOLFOX (TNT) → surgery |
| Unresectable | Fixed tumour, bilateral ureteric obstruction | TNT → reassess → multivisceral ± exenteration |
Key TNT Trials
RAPIDO (Lancet Oncol 2021): SCRT 25Gy/5fx + 18wks CAPOX/FOLFOX → surgery vs LCRT → surgery. TNT reduced disease-related treatment failure (23.7% vs 30.4%, HR 0.75). pCR 28% vs 14%.
PRODIGE 23 (NEJM 2021): mFOLFIRINOX 6 cycles → LCRT → surgery vs LCRT → surgery. 3-yr DFS 75.7% vs 68.5%. pCR 27.5% vs 12%.
OPRA (JCO 2022): Consolidation chemotherapy after LCRT → higher cCR and organ preservation rates (58% vs 43%) at 3 years.
Watch-and-Wait — Exam Essentials
| Element | Detail |
|---|---|
| cCR definition | No residual tumour on MRI (TRG 1, fibrosis only) + no ulceration/mass on endoscopy + normal CEA |
| Surveillance | DRE + flexible sigmoidoscopy Q3M × 2 years, then 6-monthly; MRI pelvis Q6M |
| Regrowth rate | ~25–30% at 2 years; ~95% of regrowths are local (salvageable by TME) |
| Outcomes (IWWD) | 5-yr OS 85%; LR 25%; DFS 94% in those without regrowth (van der Valk, Lancet 2018) |
Exam trap: cCR ≠ pCR. 15–20% of apparent cCR have residual tumour at histology. Discuss both W&W and surgery options at MDT with shared patient decision-making.
LPND — Eastern vs Western
| Approach | Practice | Evidence |
|---|---|---|
| Eastern (Japan) | Routine bilateral LPND for T3–4 below peritoneal reflection | JCOG0212: LPND reduces lateral LR (7.4% vs 12.6%); no OS difference |
| Western | LPND only if nodes ≥7mm pre-CRT remain ≥4mm post-CRT | Long-course CRT sterilises lateral nodes; LPND adds urinary/sexual morbidity |
Section 3 — Board Review / Viva
Q1. T2N0 low rectal cancer 2 cm from dentate, CRM clear 8 mm. Operation?
A: Options: APR (sphincter sacrifice) or ISR (intersphincteric resection) with ultra-low hand-sewn coloanal anastomosis. Decision: sphincter bulk on anorectal manometry, continence baseline, patient preference. No neoadjuvant for T2N0 CRM-clear.
Q2. CRM 0.5 mm anteriorly on MRI, T3c. What before surgery?
A: Threatened CRM — neoadjuvant CRT mandatory (LCRT or SCRT + consolidation). Reimage 8–12 weeks post-CRT. If still threatened — consider pelvic exenteration or ELAPE.
Q3. cCR after TNT. At 18-month surveillance, nodular irregularity at tumour site on sigmoidoscopy. What next?
A: Local regrowth (~25%). Biopsy to confirm viable tumour. If positive → salvage TME. Achieves similar R0 rates to primary surgery; sphincter preservation possible in ~60%.
Q4. LARS score >29 (major LARS) at 6 months post-ileostomy closure. Management pathway?
A: Dietary modification → loperamide → transanal irrigation (highest evidence) → biofeedback → sacral neuromodulation (SNM) for refractory major LARS.
Section 4 — Visualization
Rectal Cancer: Staging-to-Treatment Algorithm
Monograph 4 of 6
Colorectal Liver Metastases & Peritoneal Disease
CRLM · FLR · CRS/HIPEC · PCI · HAI Pump
Section 1 — Resectability & Surgical Planning
Resectability Criteria
- Adequate FLR: ≥20–25% normal liver; ≥30–40% post-chemotherapy/cirrhotic liver
- Clear surgical margin (R0, ≥1 mm)
- Preserve ≥2 contiguous hepatic segments with adequate inflow, outflow, and biliary drainage
- No unresectable extrahepatic disease
FLR% = (FLR volume) / (Total functional liver volume − tumour volume) × 100
Target FLR: ≥20% (normal liver) · ≥30% (post-chemotherapy) · ≥40% (cirrhosis)
FLR Augmentation Strategies
| Strategy | Method | Timeline |
|---|---|---|
| Portal vein embolisation (PVE) | Embolise portal vein to tumour-bearing lobe → contralateral hypertrophy | 4–6 weeks |
| ALPPS | Liver partition + PVL in single stage → rapid hypertrophy | 7–14 days (higher morbidity) |
| Two-stage hepatectomy | Resect smaller burden first, PVE, then second hepatectomy | 4–8 weeks between stages |
Section 2 — Molecular Profiling & Trials
Biomarkers Relevant to CRLM
| Biomarker | Finding | Clinical Impact |
|---|---|---|
| RAS mutant | ~55% | Anti-EGFR contraindicated; bevacizumab-based regimens |
| BRAF V600E | ~8–10% | Poor prognosis; aggressive biology; encorafenib triplet for metastatic |
| MSI-H/dMMR | ~5% metastatic | Pembrolizumab 1st line; may achieve complete responses avoiding surgery |
| RAS/BRAF WT, left-sided | ~35% | Anti-EGFR superior to bevacizumab in 1st line (FIRE-3, PEAK) |
| HER2 amplified | ~3–5% RAS/BRAF WT | Trastuzumab + pertuzumab (MOUNTAINEER) |
Key Trials
EORTC 40983 (Nordlinger, Lancet 2008): Perioperative FOLFOX4 (6 pre + 6 post cycles) significantly improved 3-yr PFS. Established perioperative chemotherapy standard.
EPOC trial (Primrose, Lancet Oncol 2014): FOLFOX + cetuximab vs FOLFOX alone perioperatively in RAS WT — cetuximab WORSENED outcomes. Avoid anti-EGFR perioperatively.
PUMP trial (Goéré, Lancet Oncol 2023): HAI pump + systemic FOLFIRI improved 2-yr OS (61% vs 50%) in liver-dominant metastatic CRC.
Section 3 — CRS/HIPEC for Peritoneal Disease
Key Concepts
| Concept | Detail |
|---|---|
| CRS (cytoreductive surgery) | Remove all visible peritoneal disease; quality measured by CC score |
| CC score | CC-0: no visible residual; CC-1: <2.5mm; CC-2: 2.5–25mm; CC-3: >25mm |
| HIPEC | Mitomycin C 38mg/m² over 90min at 42°C; or oxaliplatin |
| Patient selection | PCI ≤15–20 for CRC; no extra-abdominal disease; limited hepatic involvement |
PCI = Sum of lesion size scores (0–3) in each of 13 abdominal regions (max 39)
PRODIGE 7 (Lancet Oncol 2021): CRS alone vs CRS + HIPEC (oxaliplatin) — HIPEC did NOT improve OS (41.2 vs 41.7 months). However, CRS itself significantly improves survival vs systemic chemo alone. Most centres continue to offer CRS ± HIPEC within MDT decisions.
Section 4 — Board Review / Viva
Q1. Synchronous sigmoid cancer + 6 bilobar hepatic lesions, RAS mutant. FOLFOX + bevacizumab proposed. Surgical strategy?
A: Assess resectability at baseline and after 2–4 cycles. Options: primary-first then restage; liver-first if primary asymptomatic; simultaneous if low-risk. Cease bevacizumab ≥6 weeks before hepatectomy. PVE if FLR <25% post-chemotherapy.
Q2. PCI 18 peritoneal disease, no hepatic/extrahepatic disease, good PS. Patient asks about CRS/HIPEC.
A: PRODIGE 7 showed oxaliplatin HIPEC did not improve OS over CRS alone. CRS with CC-0 improves survival vs chemotherapy (median OS 40+ months vs ~16 months). Refer to specialist centre; discuss HIPEC on trial; PCI 18 is borderline for CC-0. Realistic expectations essential.
Q3. HAI pump — technique and rationale?
A: Catheter placed in the gastroduodenal artery (GDA) at takeoff from proper hepatic artery; pump buried in right lower quadrant subcutaneous fat. Delivers floxuridine (FUDR) — 80–90% first-pass hepatic extraction, high intratumoral concentration, minimal systemic toxicity. Collateral vessel ligation prevents extrahepatic perfusion (biliary sclerosis risk if extrahepatic).
Section 5 — Pre-Hepatectomy Protocol
| Element | Detail |
|---|---|
| Cease bevacizumab | ≥6 weeks before hepatectomy (wound healing) |
| Cease oxaliplatin | ≥4 weeks; assess for SOS (sinusoidal obstruction syndrome) via LFTs |
| CT volumetry | FLR calculation; if <25% → PVE 4–6 weeks pre-op |
| ERAS hepatectomy | No prolonged fasting · epidural for open · no drain unless biliary anastomosis · mobilise day 1 · LOS: 3–5 days lap; 5–7 days open major hepatectomy |
| Post-hepatectomy liver failure | 50–50 criteria: bilirubin >50 µmol/L + INR >1.5 at day 5 → supportive; MARS for severe |
Monograph 5 of 6
Anal Canal Tumors
SCC · AIN/HSIL · Anorectal Melanoma · Nigro Protocol
Section 1 — Anatomy & Lymphatics
| Structure | Location | Surgical Significance |
|---|---|---|
| Dentate line | Junction columnar/squamous epithelium | Above → internal iliac nodes; Below → inguinal nodes |
| Anal transition zone (ATZ) | 1–2 cm above dentate | Cloacogenic/basaloid SCC origin |
| Internal anal sphincter | Inner circular smooth muscle | Preserved in ISR; usually spared in Fournier's |
| External anal sphincter | Striated muscle, 3 loops | Voluntary continence; sacrificed in APR |
| Intersphincteric plane | Between IAS and EAS | Surgical plane for ISR; ELAPE lateral extent |
| Ischiorectal fossa | Lateral to levators | Routes fistula spread; lateral extent of anal SCC |
Section 2 — Anal SCC
TNM Staging — Anal Canal (AJCC 8th Ed)
| T Stage | Definition | N Stage | Definition |
|---|---|---|---|
| T1 | ≤2 cm | N0 | No nodes |
| T2 | >2 cm and ≤5 cm | N1a | Inguinal, mesorectal, or internal iliac |
| T3 | >5 cm | N1b | External iliac |
| T4 | Invades adjacent organ (vagina, urethra, bladder) | N1c | External iliac + any N1a |
Nigro Protocol — Exam Essentials
Current standard: 50.4 Gy (± boost to 54–59 Gy for T3–4/N+) + continuous 5-FU + mitomycin C (MMC)
| Trial | Key Result |
|---|---|
| ACT II (Lancet Oncol 2013) | MMC + 5-FU + RT vs cisplatin + 5-FU + RT — MMC non-inferior (3-yr PFS 74% vs 73%); maintenance cisplatin no benefit. MMC remains standard. |
| ACCORD-03 (JCO 2012) | Induction chemo before CRT: no benefit. Higher RT dose (60 Gy): no colostomy-free survival benefit over 45 Gy in complete responders. |
Exam trap — response assessment: Do NOT biopsy before 26 weeks post-CRT. Radiation necrosis mimics tumour on MRI/endoscopy up to 6 months. Salvage APR only for persistent disease confirmed at 26 weeks or biopsy-proven recurrence.
Section 3 — AIN / HSIL
| Grade | Old Term | WHO Term | Management |
|---|---|---|---|
| AIN I | Low-grade | LSIL | Observation; no treatment required |
| AIN II | High-grade | HSIL | Treat if symptomatic or immunocompromised |
| AIN III | High-grade (severe/CIS) | HSIL | Active treatment: WLE or ablation |
ANCHOR trial (NEJM 2022): Treatment of HSIL in HIV+ patients reduces progression to invasive anal SCC by 73% (HR 0.27). Establishes treatment of HSIL in HIV+ as evidence-based standard of care.
Section 4 — Anorectal Melanoma
- <1% of anorectal tumours; 5-yr OS ~10–20%; often amelanotic (misdiagnosed as haemorrhoid)
- Surgery: WLE (R0, 1 cm margin) vs APR — multiple series show no OS difference; WLE preferred for QoL
- Systemic: Pembrolizumab/nivolumab for metastatic (ORR ~20–25%); BRAF V600E (~30–40%) → encorafenib + binimetinib
- APR reserved for local control of large lesions or inability to achieve R0 with WLE
Section 5 — Board Review / Viva
Q1. T2N1 anal SCC (right inguinal node). Treatment plan?
A: Nigro protocol (50.4 Gy + 5-FU + MMC). Inguinal node included in elective nodal irradiation field (bilateral groins for T2+ or N1). No upfront surgery. Assess response at 8–12 weeks. Biopsy at 26 weeks if residual. Salvage APR if confirmed persistent.
Q2. Renal transplant patient on tacrolimus with AIN III perianal. Management?
A: High-risk — up to 10%/year progression in immunosuppressed. ANCHOR trial supports active treatment. HRA-guided ablation (IRC/laser) or WLE if localised. Staged ablation if >30% circumference (prevent stricture). Annual HRA post-treatment. Discuss tacrolimus reduction with transplant team if feasible.
Q3. How to distinguish cloacogenic carcinoma from rectal adenocarcinoma histologically?
A: Cloacogenic: p63+, CK5/6+, CEA−/low (SCC markers); HPV-associated; treated as anal SCC (Nigro protocol). Rectal adenocarcinoma: CK20+, CDX2+, CEA+ (glandular markers); treated as rectal cancer (surgery ± neoadjuvant CRT).
Section 6 — Perioperative Protocol (Anal SCC)
| Phase | Detail |
|---|---|
| Pre-CRT workup | HIV testing; CD4 if HIV+; EUA + mapping biopsies; MRI pelvis + CT C/A/P; PET-CT for T3–4 or N+ |
| CRT delivery | 50.4 Gy/28 fractions; 5-FU 1000 mg/m²/day D1–4 + D29–32; MMC 12 mg/m² D1 + D29 |
| Acute toxicities | Radiation dermatitis Grade 3–4 in 50%; proctitis; mucositis → emollient creams, sitz baths, low-residue diet |
| Response assessment | Clinical exam + MRI at 8–12 weeks; do NOT biopsy before 26 weeks |
| Salvage APR reconstruction | VRAM or gracilis flap for irradiated field (reduces wound breakdown from ~50% to ~15%) |
Monograph 6 of 6
Fournier's Gangrene
Necrotising Fasciitis · Polymicrobial · FGSI · Radical Debridement
Section 1 — Operative Atlas
Fascial Planes & Spread
| Fascia | Location | Relevance |
|---|---|---|
| Colles' fascia | Superficial perineal fascia (male) | Continuous with Scarpa's (abdomen) + dartos (scrotum) — primary spread plane |
| Dartos fascia | Subcutaneous scrotal layer | First plane invaded; avascular scrotal skin necrosis |
| Buck's fascia | Deep penile fascia | Limits spread to penis — penis often spared despite total scrotal loss |
| Scarpa's fascia | Abdominal wall | Continuous with Colles' → infection tracks to abdominal wall and medial thighs; NOT posterior (fascia terminates at inguinal ligament) |
Testes are usually spared: Gonadal vessels arise from the aorta — anatomically separate from scrotal fascial planes. Even with total scrotal loss, testes are often viable. Place in bilateral thigh pouches if scrotal skin fully debrided.
Debridement — Step-by-Step
| Step | Technical Detail |
|---|---|
| Positioning | Lloyd-Davies (lithotomy). Urethral catheter first. Betadine prep including lower abdomen and thighs. |
| Skin incision | Incise all necrotic skin; brown/black discolouration, no bleeding = necrotic |
| Finger test | If tissue separates with minimal resistance → necrotic → remove. Viable tissue resists. |
| Debride to bleeding margins | All necrotic skin, fat, fascia removed. Always more extensive than external appearance suggests. |
| Testicular assessment | Incise tunica albuginea — if bleeds → viable → thigh pouches. If necrotic → orchiectomy. |
| Penile/abdominal wall | Assess Buck's fascia; follow Scarpa's superiorly for abdominal wall extension |
| Wound care | Pack open. Betadine-soaked gauze. Do NOT close at first operation. |
| Return to theatre | Mandatory at 24–48 hours — disease always underestimated at first debridement |
Diverting Colostomy — Indications
Colostomy is NOT automatic. Indicated only when: rectal/anal source of infection (fistula, perforation) · extensive perianal involvement threatening sphincter · faecal contamination of wound compromising healing
Section 2 — Microbiology & Classification
Polymicrobial Organisms
| Category | Common Organisms | Role |
|---|---|---|
| Gram+ aerobes | Group A Strep, S. aureus (MRSA) | Primary invasion; exotoxin production |
| Gram− aerobes | E. coli, Klebsiella, Pseudomonas | Consume O₂; lower redox potential for anaerobes |
| Anaerobes | Bacteroides fragilis, Clostridium spp, Peptostreptococcus | Hyaluronidase + collagenase → fascial destruction; gas production |
| Fungi | Candida spp | Diabetic/immunocompromised patients; worse outcomes |
FGSI — Fournier's Gangrene Severity Index
FGSI = Sum of deviation scores for 9 physiological parameters (adapted APACHE II)
FGSI > 9 → mortality ~75% | FGSI ≤ 9 → mortality ~9%
Parameters: Temperature · Heart rate · Respiratory rate · Sodium · Potassium · Creatinine · Haematocrit · WBC · Bicarbonate
Section 3 — Emergency Protocol
Pre-operative (Actions Within 1–2 Hours)
| Action | Detail |
|---|---|
| Resuscitation | 2 large-bore IV; 500 mL crystalloid bolus; noradrenaline if MAP <65 despite 1–2 L |
| Blood cultures | Before antibiotics — but do not delay antibiotics by >1 hour |
| CT pelvis | Only if haemodynamically stable. Gas tracking along fascial planes is diagnostic. |
| Urethral catheter | Identifies urethra intraoperatively + monitors output |
| Consent | Wide debridement · possible colostomy · thigh pouches · skin grafting · testicular loss |
| ITU liaison | All Fournier's require ITU/HDU post-operatively |
Empirical Antibiotic Regimen
| Drug | Coverage | Dose |
|---|---|---|
| Piperacillin/tazobactam | Gram+, Gram−, anaerobes, Pseudomonas | 4.5 g IV 8-hourly |
| + Metronidazole | Enhanced anaerobic cover | 500 mg IV 8-hourly |
| + Vancomycin | MRSA (if risk factors) | 25 mg/kg loading, TDM-guided |
| + Micafungin | Fungal (diabetic/immunocompromised) | 100 mg IV daily |
| Alternative | Severe sepsis/high-resistance risk | Meropenem 1 g IV 8-hrly + vancomycin |
Post-operative ICU Management
| Element | Detail |
|---|---|
| Wound care | Daily dressing changes under analgesia; betadine packing → Manuka honey/silver when clean |
| Return to theatre | Planned 24–48 hrs; often 2–3 total debridements needed |
| Nutrition | Early enteral via NG; 25–30 kcal/kg/day; 1.5 g/kg/day protein |
| Glycaemic control | Target 6–10 mmol/L; insulin infusion; hyperglycaemia impairs healing + immunity |
| VAC therapy | Once wound clean and granulating (~2–3 debridements); accelerates granulation |
| STSG | Split-thickness skin graft at 2–4 weeks when granulation complete |
| HBO | Adjunctive only at centres with availability; Level III evidence; never delays surgery |
| Mortality | Overall 15–40%; FGSI >9 → ~75%. Surgery is the single most time-sensitive intervention. |
Section 4 — Visualizations
Fournier's Gangrene — Fascial Spread Zones
Fournier's Gangrene — Emergency Management Pathway
Quick Reference
Master Exam Summary
One-page rapid revision — all six monographs
| Domain | Must-Know Trial | Key Classification | Exam Trap |
|---|---|---|---|
| Benign Polyps / FAP / Lynch | CAPP2 (aspirin in Lynch, HR 0.63); Amsterdam II criteria | Haggitt (L4 = surgery); Kikuchi Sm1/2/3; Paris classification; Polyposis gene table | MSI-H Stage II: do NOT give 5-FU alone. MAP is autosomal recessive. |
| Colon Cancer (CRC) | IDEA (3 vs 6 months adjuvant); KEYNOTE-177 (pembrolizumab 1st line MSI-H); BEACON (BRAF V600E triplet) | TNM 8th Ed; Clavien-Dindo; AJCC stage grouping | EPOC trial: anti-EGFR perioperatively WORSENS outcomes (even in RAS WT). Adjuvant bevacizumab not proven. |
| Rectal Cancer | RAPIDO (TNT with SCRT); PRODIGE 23 (FOLFOX + LCRT); OPRA (organ preservation); IWWD (W&W database) | TRG Mandard 1–5; CRM definition (≤1mm); T3 subclassification; ESMO risk groups | cCR ≠ pCR (15–20% residual tumour). W&W regrowth ~25% at 2 yrs. ROLARR: robotic = laparoscopic CRM+. |
| CRLM & Peritoneal | EORTC 40983 (perioperative FOLFOX); PRODIGE 7 (HIPEC no OS benefit); PUMP (HAI pump OS benefit) | FLR% formula; PCI (0–39); CC score (0–3) | PRODIGE 7: oxaliplatin HIPEC did NOT improve OS. EPOC: no anti-EGFR perioperatively. Cease bevacizumab ≥6 weeks pre-hepatectomy. |
| Anal Canal Tumors | ACT II (MMC vs cisplatin — MMC non-inferior); ACCORD-03 (no benefit from induction chemo/dose escalation); ANCHOR (HSIL Rx reduces SCC in HIV+, HR 0.27) | AJCC 8th anal SCC TNM; AIN grading (LSIL/HSIL); lymphatic drainage (dentate line landmark) | Do NOT biopsy for response before 26 weeks post-CRT. Cloacogenic = anal SCC (Nigro), NOT rectal adenocarcinoma. Anorectal melanoma: WLE = APR for OS. |
| Fournier's Gangrene | Surviving Sepsis 2021 (vasopressor guidance); FGSI validation studies | FGSI >9 = ~75% mortality; Clavien-Dindo for complications | Colostomy not automatic — only if colorectal source/faecal contamination. Testes usually spared (gonadal vessels independent). Posterior spread uncommon. 2nd look at 24–48 hrs is mandatory. |
High-yield exam facts — rapid fire
- Haggitt level 4 / Kikuchi Sm3 / LVI / margin <1mm → surgery for malignant polyp
- Amsterdam II 3-2-1 rule: ≥3 relatives, ≥2 generations, ≥1 <50 yrs
- MSI-H Stage II: no 5-FU; Stage III: FOLFOX × 6 months; Metastatic: pembrolizumab 1st line
- CRM threatened (≤1mm): neoadjuvant mandatory before surgery
- W&W regrowth: ~25–30% at 2 years; 95% are local and salvageable by TME
- FLR target: ≥20% normal; ≥30% post-chemotherapy; ≥40% cirrhotic
- PRODIGE 7: CRS ± HIPEC — HIPEC (oxaliplatin) did NOT improve OS
- Anal SCC response assessment: do NOT biopsy before 26 weeks post-CRT
- ANCHOR trial: treating HSIL in HIV+ reduces anal SCC risk by 73%
- Fournier's FGSI >9: ~75% mortality; surgery is the single most time-sensitive factor
- Testes in Fournier's: usually spared (gonadal vessels from aorta, not scrotal fascia)
- Fournier's colostomy: only if colorectal source or faecal wound contamination