Malignant Neoplasms of the Anal Canal

Background: Malignant neoplasms of the anal canal are rare accounting for approximately 4% of all colorectal malignancies. Objectives: The present study aimed to report the clinicopathological characteristics and treatment outcomes of 41 cases with malignant neoplasms of the anal canal. Patients and Methods: Between 1999 and 2012, 41 consecutive patients were diagnosed with primary malignant neoplasm of the anal canal which were treated and followed up at Namazi hospital. Only primary malignant tumors arising from the anal canal were included. Patients with secondary anal canal involvement from rectal or perianal skin cancers and metastatic tumors were excluded. Results: There were 22 women and 19 men, age ranging from 33 to 83 years, with a median age of 57 years at diagnosis. Sixteen patients (39%) had localized disease, 21 (51%) had regional disease, and 4 (10%) had metastatic disease at diagnosis. Squamous cell carcinoma (61%) was the most frequent histologic subtype, followed by adenocarcinoma (27%), malignant melanoma (10%), and gastrointestinal stromal tumor (2%). After a median follow-up of 51 (11-169) months for surviving patients, 22 patients were alive and without disease, three were alive with disease, and 19 patients died due to the disease. Histological subtype (P = 001), and stage of disease (P = 0.002) were prognostic factors for overall survival. The 5-year local control, disease-free, and overall survival rates for all patients were 63.9%, 53%, and 59.4% respectively. Conclusions: This study indicated that squamous cell carcinoma, adenocarcinoma, and malignant melanoma are the most frequent malignant neoplasms in the anal canal. Histological subtype and disease stage are the most important prognostic factors for overall survival in this region.