The purpose of this study is show that intensity-modulated radiotherapy (IMRT), as compared with conventional radiotherapy, improves the precision of tumor targeting and reduces the acute and late effects of radiation toxicity when used to treat anal cancer. Results from this work will provide a basis for incorporating the use of IMRT to treat anal cancer in future treatment protocols.

The objectives of this study are three-fold. First, we would like to learn and compare the doses of radiation received by the tumor and the normal tissues in anal cancer patients treated with IMRT, and in those treated with conventional radiotherapy. Second, we wish to compare the acute effects of radiation treatment in both groups of patients. Our third objective is to evaluate the late effects of radiation treatment in both groups of patients. The first two objectives will be studied using a retrospective analysis of patients with anal cancer treated at Stanford University Medical Center. The third objective will require these patients to complete and return three quality of life questionnaires.

Inclusion Criteria:Histologically confirmed diagnosis of squamous cell carcinoma of the anus. Must be able to provide informed consent.
 Exclusion Criteria:History of new malignancy since the time of treatment for anal cancer. Non-English speaking.