Abstracts
2002 Digestive Disease Week

# 100410 Abstract ID: 100410 Colorectal Cancers at the Rectosigmoid Junction: Should They Be Treated as Colon or as Rectal Cancer?
Clifford Y Ko, Jonathan Sack, Los Angeles, CA

Introduction: While the rectosigmoid area is small, 1 in 10 of all colorectal cancers occur at this junction. Currently, it is debated whether to treat rectosigmoid cancers as a colon or a rectal cancer. Clearly, this has important implications regarding use of adjuvant therapy (i.e. use of radiation therapy (XRT) and the specific stage for use of adjuvant therapy) and may lead to 'overuse' or 'underuse' issues. No guidelines for these cancers exist; furthermore, no outcomes data specific to rectosigmoid cancers are available. The current study uses a nationwide, population-based cancer registry to formally characterize how rectosigmoid cancers are currently being treated. Outcomes survival data are also analyzed. Methods: All cases classified as rectosigmoid cancer from 1972 to 1998 were identified in the SEER national cancer registry. The use of XRT therapy was characterized for the overall cohort, as well as with regard to age, gender, race, stage of cancer, and other associated variables. Finally, survival analyses were performed to understand the efficacy of XRT. Results: A total of 12,223 rectosigmoid cancer cases were identified. Mean age was 68 years; 55% were male. 28% were stage II and 28% were stage III. Over 95% underwent cancer directed surgery. Most patients who had no surgery had stage IV disease and/or had medical contraindications. Regarding XRT, 27% of all stage II rectosigmoid cancers underwent XRT, while 39% of stage III had XRT. In a multivariate logistic regression to predict the use of adjuvant XRT, significant gender, age, and racial differences were seen. More males (p<0.0001) and less elderly (p<0.0001) underwent XRT. Also less Blacks (p=0.01) and less Asians (vs. Whites, p=0.001) underwent XRT. Of note, 5-year survival was significantly higher for stage 3 patients who underwent XRT (54% vs 49%, p=0.02). Conclusions: This study shows that a significant variation in the treatment of rectosigmoid cancers exists in the population, which may be affecting survival. While part of the problem may be the anatomic definition of the rectosigmoid region, it is clear that further work is also needed regarding the efficacy, side effects, as well as disparities concerning adjuvant therapy for these cancers.