Anal Cancer: Clinical Presentation and Diagnostic Work-Up
Typical Symptoms
Anal cancer most commonly presents with rectal bleeding (78%), but diagnosis is frequently delayed because bleeding is mistakenly attributed to hemorrhoids. 1
The complete symptom profile includes:
- Bleeding (78% of patients) - the most common presenting symptom 1, 2
- Anal or perianal pain (63% of patients) 2
- Palpable mass or foreign body sensation (22% of patients) 2
- Pruritus (itching) 1
- Discharge 1
- Fecal incontinence 1
- Fistulae 1
- Weight loss (31% of patients) - particularly associated with locally advanced disease 2
- Non-healing ulcer 1
Critical Clinical Pearls
Patients with locally advanced disease (T3/T4) present with significantly more symptoms than those with T1/T2 disease. 2 On multivariate analysis, perianal pain, painful defecation, and weight loss are significantly associated with T3/T4 disease and should raise suspicion for advanced cancer. 2
Approximately 20% of patients may be asymptomatic, though 95% will have at least one finding on physical examination. 2, 3
Mandatory Diagnostic Work-Up
Digital anorectal examination (DRE) is an essential, low-cost clinical tool for detecting anal lesions and must be performed in all suspected cases. 1
Initial Evaluation (Mandatory)
- Complete medical history 1
- Full clinical examination including DRE 1
- Biopsy - histological confirmation is mandatory as multiple histopathological entities can mimic squamous cell carcinoma, including adenocarcinoma, melanoma, gastrointestinal stromal tumors, poorly differentiated neuroendocrine tumors, and lymphoma 1
- Vaginal examination in women - particularly for low, anteriorly placed tumors to assess vaginal/vaginal septal involvement 1
- Inguinal lymph node palpation - especially superficial inguinal nodes medial and close to the pubis 1
Recommended Staging Studies
- High-resolution pelvic MRI - optimal for assessing local tumor extent and anatomic relationships 1
- CT of thorax, abdomen, and pelvis - for distant staging 1
- PET-CT - recommended for comprehensive staging 1
- HIV testing - should be considered in all patients with unknown HIV status 1
- P16/HPV assessment 1
- Anoscopy/proctoscopy 1
- Gynecological examination in women 1
Optional Studies
- Endo-anal ultrasound 1
- Ultrasound-guided fine needle aspiration (FNA) of suspicious inguinal nodes 1
- Examination under anesthesia 1
Important Caveats
Colonoscopy is NOT required for anal cancer work-up, as synchronous colonic lesions are not reported with squamous cell carcinoma of the anus. 1
All suspicious anal lesions should be excised or biopsied - do not assume benign pathology based on appearance alone. 1
Female patients with anal intraepithelial neoplasia (AIN) should be screened for synchronous cervical, vulvar, and vaginal intraepithelial neoplasia given the shared HPV etiology. 1
The presence of a large obstructing mass or tumor with associated fecal incontinence may require defunctioning stoma consideration, though this decision should be weighed carefully as most initial colostomies are not reversed. 1