Behavior and Characteristics of Squamous Cell Carcinoma of the Perianal Region: A Pilot Study

Abstract

Introduction: We believe perianal Squamous Cell Carcinoma (SCC) is not well represented by current American Joint Committee on Cancer (AJCC) staging guidelines. We thus propose a modified staging system to better predict the behavior of aggressive perianal SCCs. Methods: A retrospective cohort review of 566 patients treated at the MGH and BWH for cancers involving the perianal area was performed. Data on comorbid conditions, tumor characteristics and long term outcomes was collected. Results: Fifty-two patients meeting the inclusion criteria for the study were identified. There were 6 local recurrences, 2 nodal metastases, 4 distant metastases, and 3 disease specific deaths. Patients aged 55 years or older, those with tumor diameters of 3 cm or higher, and those who were HPV infection positive are at greater risk of a poor outcome among patients diagnosed with perianal SCC. Additionally, 60% of high-stage tumors by BWH-T had a poor outcome, while 0/1 high-stage AJCC tumors had a poor outcome. Conclusions: The distinction between perianal SCC and SCC involving the anal canal is difficult to make on either clinical or histologic grounds. Treatment with either resection or chemoradiation is pursued currently, with uncertain differences in outcomes. This study identifies several factors which independently predict a poor outcome, including: age greater 55, HPV positive status, and tumor diameter >3cm. Additionally, the BWH-T staging guidelines appear to better predict poor outcomes than the AJCC anal or cutaneous guidelines.