A Minimally Invasive Surgical Approach to Synchronous Anal and Colon Adenocarcinoma: Review of Existing Literature

Abstract

Dear Editor:Neoplasms of the anal canal are extremely rare, accounting for about 1 % of all gastrointestinal tumors and less than 5 % of anorectal malignancies. According to the latest WHO classification, growths in the anal canal can be broadly categorized into epithelial, mesenchymal, and secondary tumors. Squamous cell carcinoma (SCC) and adenocarcinoma of the anal canal (ACC) both arise from the epithelium; however, while SCCs represent the majority of epithelial anal cancers at 80 %, adenocarcinomas make up less than 10 %.In contrast with the more common SCC, diagnosis of ACC has been associated with a poor prognosis due to a multitude of factors. These include its more aggressive natural history as well as its tendency to present similarly to benign anal conditions hence, resulting in delayed diagnosis. The low incidence of ACC has also resulted in a paucity of studies and a lack of defined recommended treatment modalities in comparison with the more widely studied SCC.The lack of a definitive set of treatment guidelines for ACC means that treatment options remain widely varied. While some studies recommend primary chemoradiotherapy as the first line of treatment, recent studies have demonstrated an increasing preference towards surgical resection with neoadjuvant or adjuvant chemoradiotherapy.The prevalence of synchronous colorectal carcinomas is also relatively low, with a reported range of 1.1 to 8.1 %. It is defined by the presence of two or more lesions detected either pre/intraoperatively or within 6 months post-operatively and located at least 4 cm apart in the absence of any submucosal spread. The management strategies proposed are extremely diverse and largely determined by patient demographics and tumor characteristics. While evidence remains limited, minimally invasive surgery (MIS) has been shown to be a feasible option in the management of synchronous colorectal lesions.We present the first documented case of synchronous anal and colon adenocarcinomas of separate distinct origin, for which primary surgical resection of both tumors were performed via a MIS approach as well as review the current literature and present the current evidence for the management of anal adenocarcinoma.A 70-year-old Asian gentleman presented with an anal mass of 5-year duration that had gradually been increasing in size. It was associated with per rectal bleeding over 2 to 3 years, with a decreased stool caliber and tenesmus experienced during defecation. Systemically, he had significant loss of weight of 10 to 15 kg over a 6-month period.He had no significant past medical history apart from the history of a perianal mass for the past 5 years for which he did not seek medical attention. Prior to that, he gives a longstanding history of perianal pain and discharge, suggestive of the presence of a chronic peri-anal fistula. He has no personal or family history of cancers and was a heavy smoker of 40 pack years. His performance status was good, with an Eastern Cooperative Oncology Group (ECOG) score of 0.Physical examinat...