Locally advanced anal small cell carcinoma with durable complete response to chemoradiation followed by consolidation chemotherapy: case report and literature review.

Extrapulmonary small cell carcinoma (EPSCC) is a rare and aggressive clinical entity that can involve a variety of anatomic locations, including the gastrointestinal tract. Involvement of the gastrointestinal tract is associated with a particularly poor prognosis with patients often presenting with widespread dissemination on initial clinical presentation or rapidly progressing to systemic disease from locoregional involvement. Primary small cell carcinoma of the anal canal is extremely rare, with limited published case reports in the literature. As a result, management of this disease is not well defined, and outcomes are poor with high rates of disease relapse. We report a patient with locally advanced anal small cell carcinoma after presenting with irregular bowel movements, changes in stool caliber, and rectal bleeding for two months and achieved a durable complete response to concurrent chemoradiation with cisplatin and etoposide followed by consolidation chemotherapy and discuss our current understanding of this disease. Specifically, we review the epidemiology, risk factors, clinical course, the treatment strategies over the past two decades, and prognosis for EPSCC. Finally, we conclude our discussion by reviewing the rationale of our treatment regimen and the potential role and benefit of consolidation therapy in the management of this rare and aggressive disease. 2021 Journal of Gastrointestinal Oncology. All rights reserved.