Accuracy of Endoanal Ultrasound in the Follow-up Assessment for Squamous Cell Carcinoma of the Anal Canal Treated with Radiochemotherapy

Background: Radiochemotherapy has largely replaced surgery in the treatment for squamous cell cancer of the anal canal. Transanal ultrasonography is well documented as an important investigation method in the management of anal carcinoma. This study aimed to evaluate the accuracy of endoanal ultrasound in the study of the postradiation findings and to distinguish between postradiation fibrosis, residual tumor, and local recurrence.

Methods: The study enrolled 16 consecutive patients with biopsy-proven squamous carcinoma of the anal canal between 2003 and 2006. All the patients underwent a pretreatment and at least four posttreatment endosonographies, according to the follow-up period. All the patients were treated with the same radiochemotherapy protocol.

Results: Nine patients had stage uT2 disease; none had uT3 disease; and seven had uT4 disease. There was no evidence of residual tumor in the T2 group after treatment. In the T4 patients after treatment, ultrasound demonstrated tumor regression or abnormalities considered to be radiation-induced changes rather than residual diseases. Only for three patients was a posttreatment biopsy performed to evaluate recurrence (two uT2 and one uT4). Surgical treatment of recurrence was performed for two uT4 patients.

Conclusions: Endoanal ultrasound is a safe and effective method for evaluating and following anal cancer before and after treatment. Experience and evaluation during the period of the ultrasonographic abnormalities could give a clear idea concerning the evolution of the anal tumors treated with radiochemotherapy.