For Ca Anal canal t/t of choice is -

Nigro regimen refers to combined chemotherapy and radiotherapy for primary treatment of malignant tumors of the anal canal. In the 1970s, Nigro pioneered preoperative combination chemoradiation therapy to convert unrespectable cases to respective cases. There was no surgical pathological evidence of tumor found in three out of three patients treated with this approach in an early report. This led to the concept of definitive radiation therapy combined with chemotherapy. Prior to this, the standard definitive treatment for carcinoma of the anal canal was abdominal-perineal resection, which necessitated a permanent colostomy. The organ preservation concept following the discovery of a high complete response rate from combined chemoradiation saves a large number of patients from undergoing abdominal-perineal resection and colostomy.