[Lymphatic mapping and inguinal sentinel lymph node biopsy in anal canal cancers to avoid prophylactic inguinal irradiation].

Thirty-five patients with clinically N0 cancers of the canal anal, 33 epidermoid carcinomas et 2 melanomas were histologically staged with inguinal sentinel lymph node biopsy (ISN). With the combined technique, blue dye and radiocolloid the ISN was identified in 100% of the cases. The ISN was invaded in 7 cases/33 for epidermoid tumors and 2/2 for melanomas. After 18 months of follow-up, no inguinal recurrence could be seen in ISN pN0 cases. In conclusion, ISN biopsy is a reliable procedure to stage anal canal cancers. It should prevent unnecessary prophylactic inguinal irradiation for pN0 ISN. Inguinal irradiation is only indicated in pN1 ISN.