Radiation therapy of recurrent anal squamous cell carcinoma in-situ: a case report.

Introduction: High-grade anal intraepithelial neoplasia, also referred to as anal squamous carcinoma in-situ, or Bowen's disease of the anus, make up less than 1% of all digestive system cancers in the United States. The treatment of choice is surgical resection with anal mapping. However, this disease often recurs or persists, requiring additional surgery for these patients. This can compromise the anal sphincter leading to leakage. In this case report, we discuss the efficacy of radiation therapy as a modality to treat post-excisional recurrent Bowen's disease, which may prevent sphincter compromise, leading to improved quality of life.

Case Presentation: An 84-year-old Caucasian woman presented with post-excisional persistent/recurrent squamous cell carcinoma in-situ. The initial lesion measured 3 cm in diameter on the right lateral side of the anal margin. A standard surgery consisting of wide local excision with anal mapping was performed. The margins were clear and our patient was followed up. Our patient recurred with a 1.2 x 0.8 cm lesion on the left anal verge extending to the anal canal. A biopsy along with mapping was done, and 2 of the 17 mapping specimens were positive for carcinoma in-situ, one in the anal canal. Due to the location of the positive anal mapping, and in order to prevent sphincter compromise on re-excision, our patient was offered definitive radiation therapy. Two years after radiation therapy, our patient showed no signs of recurrent disease and had good sphincter control.

Conclusion: Although the main treatment modality for treating persistent/recurrent Bowen's disease is surgery, an alternative approach using external beam radiation for CIS may be enough to provide a cure for some patients with recurrent disease.