Indications for and results of combined modality treatment of colorectal cancer.

Combined modality chemoirradiation is commonly used as a component of treatment in combination with maximum resection for both high-risk resectable and locally advanced primary or recurrent rectal cancers. With surgically resected but high-risk rectal cancers, postoperative chemoirradiation has been shown to improve both disease control (local and distant) and survival (disease-free and overall) and was recommended as standard adjuvant treatment at the 1990 National Institute of Health (NIH) Consensus Conference on Adjuvant treatment for patients with rectal and colon cancers. Subsequent intergroup trials are being conducted to help define optimal combinations of postoperative chemoirradiation for resected high-risk rectal cancers and to test sequencing issues of preoperative versus postoperative chemoirradiation. With locally unresectable primary or recurrent colorectal cancers, standard therapy with surgery, external beam irradiation (EBRT) and chemotherapy is often unsuccessful. When intraoperative electron irradiation (IOERT) is combined with standard treatment, local control and survival appear to be improved in separate analyses from the Mayo Clinic and the Massachusetts General Hospital (MGH). However, routine use of systemic therapy is also needed as a component of treatment, in view of high rates of systemic failure.