Does a rectal cancer of the upper third behave more like a colon or a rectal cancer?

PURPOSE: This study aimed to evaluate whether cancers in the upper third of the rectum should be treated according to colon or rectal cancer guidelines.
METHODS: We evaluated 499 patients with tumors located in the sigmoid colon (299 patients, 60%), the upper third of the rectum (95 patients, 19%), or the middle third of the rectum (105 patients, 21%), International Union against Cancer tumor stage II or III, no preoperative radiochemotherapy, and primary curative tumor resection between 1990 and 2006. Patients' surgical, histopathological, and prognostic parameters were compared. The median follow-up time was 80 months.
RESULTS: Patients with sigmoid cancer showed a trend of significantly better estimated cause-specific survival (5-y value +/- 95% CI: 83.6 +/- 4.7%) compared with patients with rectal cancers of the upper third of the rectum (5-y value +/- 95% CI: 74.3 +/- 9.6%) or the middle third of the rectum (5-y value +/- 95% CI: 73.4 +/- 9.2%) (P = .063). Tumor location was an independent prognostic parameter (P = .036), with an increased risk of cause-specific death for rectal cancers of the upper third (hazard ratio, 1.87; P = .007) and of the middle third (hazard ratio, 1.43; P = .022) compared with sigmoid cancers. Stratification of upper third rectal cancers according to tumor grade, tumor infiltration depth (pT), and lymph node status (pN) identified a high-risk group.
CONCLUSIONS: Cancers of the upper third of the rectum have more similarities with rectal cancers of the middle third of the rectum than with sigmoid cancers. A subgroup of patients with upper third rectal cancer can be identified who may require a more aggressive therapy than only primary resection followed by adjuvant therapy.