6. Rectal Cancer

Rectal cancer – one-breath summary

Adenocarcinoma of the rectum • Presents with rectal bleeding • Colonoscopy + biopsy to diagnose • MRI pelvis decides treatment • RT BEFORE surgery:    ◦ 25 Gy/5, or    ◦ 45–50 Gy + capecitabine • Then TME surgery

Rectal cancer – WHO (risk factors)

• Older age • Red / processed meat, low fibre • Obesity, smoking, alcohol • Ulcerative colitis • Family syndromes:    ◦ FAP (familial adenomatous polyposis)    ◦ Lynch syndrome

Rectal cancer – WHAT (histology)

• Adenocarcinoma (> 90%) • Grows from a polyp: adenoma → carcinoma

Rectal cancer – SIGNS

• Bleeding from the bottom • Change in bowel habit • Tenesmus (feeling of not emptying) • Anaemia

Rectal cancer – SCANS

• DRE (finger exam) • Colonoscopy + biopsy • CEA blood marker • MRI pelvis = MOST IMPORTANT    ◦ Depth of tumour    ◦ Lymph nodes    ◦ Distance to mesorectal fascia (≤ 1 mm = threatened) • CT chest/abdomen → liver & lung spread

What is the mesorectal fascia (and TME)?

• Mesorectal fascia = the edge of the fatty envelope around the rectum • The surgeon cuts along it • Tumour ≤ 1 mm from it = "threatened margin" → needs chemoradiotherapy first • TME = Total Mesorectal Excision = removing rectum + its fatty envelope

Rectal cancer – STAGE (TNM)

• T1 inner layer (submucosa) • T2 muscle • T3 through the wall into fat • T4 other organs • N1 = 1–3 nodes • N2 = 4+ nodes

Rectal cancer – TREAT

• Early (T1–T2, no nodes) → surgery (TME) alone • Medium risk → short-course RT → surgery • High risk / threatened margin → long-course chemo + RT → surgery • Very high risk → TNT (all chemo + RT before surgery) • Tumour gone after treatment → "watch and wait" • Palliative → short RT for bleeding / pain

DOSE: Rectum short-course RT

• 25 Gy / 5 (5 Gy × 5)

DOSE: Rectum long-course chemoradiotherapy

• 45–50.4 Gy / 25–28 • + capecitabine (oral 5-FU)

DOSE: Rectum palliative RT

• 30 Gy / 10 or 25 Gy / 5

Rectal RT – side effects

• Acute: diarrhoea, sore bottom, bladder irritation • Late:    ◦ Bowel urgency (LARS = low anterior resection syndrome)    ◦ Sexual problems

Rectal cancer – memory hook

"5 × 5 or 45 + ca