Lower gastrointestinal malignancies

Objective: This refresher course will review the current knowledge as well as ongoing and future research strategies in lower gastrointestinal malignancies. Radiation therapy has a significant role in the adjuvant treatment of lower gastrointestinal malignancies. Furthermore, there are data to suggest that radiation therapy is an integral component of the conservative management (organ preservation) of rectal and anal cancers. 1. Colon cancer. The standard adjuvant treatment for node positive or high risk transmural colon cancer is postoperative 5-FU and Levamisole. There are retrospective data to suggest that certain subsets of high risk patients may benefit from postoperative radiation therapy. 2. Rectal cancer. Randomized trials have revealed an advantage of postoperative radiation therapy plus chemotherapy in transmural and/or node positive rectal cancer. In the adjuvant setting the use of continuous infusion 5-FU may be more beneficial compared with bolus 5-FU. Despite the improvement in survival, postoperative therapies are associated with an approximately 35% incidence of grade 3+ toxicity. Recent data suggest that the use of preoperative combined modality therapy may be associated with less toxicity as well as increase the chance of sphincter preservation. New Intergroup trials addressing these issues will be presented. In patients with locally advanced unresectable rectal cancer, the addition of intraoperative radiation therapy may further improve local control. 3. Anal cancer. The use of combined 5-FU/Mitomycin-C and pelvic radiation therapy is effective in the treatment of anal carcinoma. The RTOG has recently completed a randomized trial addressing the question of the effectiveness and toxicity of Mitomycin-C. The replacement Intergroup Phase III trial will be presented