Rectal Cancer Warning Signs: Symptoms That Warrant Evaluation

Rectal cancer often presents with local symptoms due to anatomic location. Early detection dramatically improves survival (Stage I 5-yr OS >90%).

Red-Flag Symptoms

• Hematochezia: Bright red blood per rectum or mixed with stool (never assume hemorrhoids).
• Change in caliber: Narrow, pencil-thin stools.
• Tenesmus: Persistent urge to defecate with little output.
• Incomplete evacuation sensation.
• Altered bowel habits: New-onset constipation/diarrhea alternating.
• Pelvic/rectal pain, pressure.
• Unexplained weight loss, fatigue (anemia).
• Palpable mass on DRE.

Diagnostic Pathway

1. Digital rectal exam (DRE) – detects 40–60% of rectal cancers.
2. Colonoscopy with biopsy (gold standard).
3. MRI pelvis (local staging: T, N, CRM, EMVI).
4. CT chest/abdomen/pelvis (distant mets).
5. CEA baseline.

Screening

Average risk: colonoscopy at 45 (USPSTF). Earlier/frequent if family history, IBD, genetic syndrome.