Carcinoma of the anal canal. A clinical and pathologic study of 188 cases.

Among 188 patients presenting with carcinoma of the anal canal the predominant cell types were squamous cell (56%) and nonkeratinizing basaloid (35%). Thirteen patients who had predominantly small (less than or equal to 2 cm) and only superficially invasive squamous cell lesions were treated with local excision, and although one required later abdominal perineal (AP) resection for local recurrence, all were apparently cured. Local excision should be preferred as initial treatment for such lesions. One hundred eighteen patients with squamous cell and nonkeratinizing basaloid carcinomas were primarily treated with AP resection. The operative mortality rate was 2.5%. Among 114 patients who survived surgery and had adequate follow-up, 40% developed recurrent disease, and 71% have survived 5 or more years. Pathologic staging based on depth of tumor invasion and regional nodal involvement was strongly predictive of survival as was tumor histology with progressively poorer survival rates from low-grade squamous cell to high-grade squamous cell to nonkeratinizing basaloid types. Tumor size was inversely related to prognosis and was strongly associated with stage. Squamous cell anal carcinoma was dominantly a local disease with approximately 70% of patients presenting with tumor apparently limited to the bowel wall, only 20% with regional node involvement and only 2% with distant metastasis. Even among those patients who recurred after AP resection approximately 80% had all known disease still limited to the pelvic area. Corresponding figures for nonkeratinizing basaloid tumors were 50 percent presenting limited to the bowel wall, 30% with regional nodes, 20% with distant metastasis, and 60% with initial recurrence limited to the pelvis. Among the 13 patients studied with small cell anal carcinoma, the authors found the disease to be very virulent either initially presenting with or rapidly evolving into diffuse dissemination. Only one of the seven patients who could be treated surgically survived 5 years. As is true for small cell carcinomas primary to other sites, this neoplasm should be regarded as a systemic disease. With these findings as a foundation, possible future strategies for management of anal carcinoma are discussed.