Definitive chemoradiotherapy for a patient with anal cancer after renal transplantation

Patients after renal transplantation are susceptible to secondary malignancies, including anal squamous cell carcinoma. Chemoradiotherapy is the standard treatment for anal squamous cell carcinoma; however, typical irradiation fields for anal cancer encompass a transplanted kidney located in the right iliac fossa, which causes complete renal dysfunction. Thus, typical irradiation fields are not feasible for this population. Additionally, standard concurrent chemotherapy demonstrates nephrotoxicity. Here, we report a case of modified definitive chemoradiotherapy for a 40-year-old patient with locally advanced perianal squamous cell carcinoma after renal transplantation whose abdominoperineal resection was difficult because of a history of repeated open surgeries and long-term steroids. We modified the cranial side of the elective nodal irradiation fields in this case to spare the transplanted kidney, considering the lymph chains of the perianal tumor. We then used continuous 5-fluorouracil to avoid nephrotoxicity of mitomycin C, considering his life expectancy. Modified definitive chemoradiotherapy achieved complete remission with expected toxicities. Now, approximately five years after the procedure, the patient remains disease-free, preserving anal and renal function. Definitive chemoradiotherapy using modified irradiation fields and chemotherapy may be an option for patients with anal squamous cell carcinoma after renal transplantation.