Pocket Oncology (Pocket Notebook Series), 1st Ed.

RECTAL CANCER

Dmitriy Zamarin and Leonard Saltz

Epidemiology

• See colon cancer

Risk Factors

• See colon cancer

Genetics

• See colon cancer

Pathology

• See colon cancer

Clinical Presentation

• See colon cancer

Screening

• See colon cancer

Figure 15-3 Anatomy of rectum

General Diagnostic Evaluation

• Colonoscopy

• CT of chest abdomen & pelvis

• LFTs, CEA

• KRAS Mt status in pts w/met disease

• MSI testing or IHC for MMR proteins in pts <50

Diagnostic Evaluation for Localized Staging

• Transrectal ultrasound (TRUS): 80–95% accuracy of distinction between T1/2 vs. T3 tumors. Operator dependent. Inadequate for deeply invasive tumors or evaluation of distant iliac adenopathy

• MRI: High degree of accuracy for prediction of circumferential resection margin or CRM (MERCURY BMJ 2006;333:779), less operator dependent, allows for study of stenotic tumors & pelvic adenopathy

• Both modalities may provide complementary info

• CT: Helpful for staging distant met spread, limited for local tumor & nodal staging

• PET: Offers no additional significant info for locoregional staging but can be useful for localizing tumor in RT planning

Clinical Staging & Treatment

Principles of Surgical Resection:

• Total mesorectal excision (TME): Removal of the perirectal areolar tissue & includes the lateral & circumferential margins of the mesorectal envelope. Improved local control & ↑ survival rates (Lancet1993;341:457)

• Regional LND: Dissection of mesorectum & the regional LN (>12 LN)

Surgical Procedures & Criteria

• Local excision: Transanal, trans-sphincteric, or posterior parasacral approach

Criteria

T1 CAs

No radiographic evidence of LN involvement

Mid- to distal rectal location

Tumors <3 cm in diameter & <30% circumference of bowel

Clear margin

No high-risk features (poorly differentiated, LVI, PNI)

Reliable postoperative surveillance

• Sphincter-sparing resection (eg, low anterior resection, coloanal resection): Removes sigmoid colon & rectum to the level of clear distant margin

Criteria

Invasive rectal CAs beyond the submucosa

Histologically proven negative distal margin

• Abdominoperineal resection (APR): Involves resection of the sigmoid colon, rectum, & anus, w/construction of permanent colostomy

Criteria

Negative distal margin of resection cannot be achieved w/sphincter-sparing procedures

Salvage procedure for local recurrence or locally adv rectal CA

Principles of Radiation & Chemoradiation

• Adjuvant RT reduces local recurrence, but has no OS benefit

• Adjuvant chemoradiation is superior to adjuvant RT alone w/OS benefit (NEJM 1994;331:502)

• Neoadj chemoradiotherapy is superior to adjuvant chemoradiotherapy w/↓ local relapse rate & ↑ tolerance, but no OS benefit (NEJM 2004;351:1731)

• Neoadj chemoradiotherapy w/infusional 5-FU is superior to radiation alone w/improved response & local control (NEJM 2006;355:1114)

• No benefit of addition of OX or irinotecan to 5-FU during radiation

• Neoadj chemoradiation w/Cap is equivalent w/chemoradiation w/infusional 5-FU (Lancet Oncol 2012;13:579)

• Current guidelines: 45–50 Gy in 25–28 fractions to the pelvis concurrent w/infusional 5-FU or Cap in the neoadj setting

Principles of Adjuvant Chemotherapy in Early Stage Disease

• No direct evidence for benefit of adjuvant chemotherapy after preoperative chemoradiation, but FOLFOX/CapeOX are recommended as extrapolation from colon CA data (MOSAIC NEJM 2004;350:2343)

• Postoperative Rx is indicated in all pts who receive preoperative Rx regardless of pathology results from resection

Surveillance After Initial Therapy

• Hx & physical every 6 mos for 5 y

• CEA every 6 mos for 5 y

• CT of chest/abdomen/pelvis annually for 5 y

• Colonoscopy in 1 y; if no adv adenoma repeat in 3 y, then every 5 y

• Endoscopic evaluation of anastomosis site every 6 mos for pts post LAR

Chemotherapy in Advanced & Metastatic Disease

• See colon cancer