Adenocarcinomas of the upper third of the rectum and the rectosigmoid junction seem to have similar prognosis as colon cancers even without radiotherapy, SAKK 40/87.

Purpose: To investigate the prognosis of adenocarcinomas of the upper third of the rectum and the rectosigmoid-junction without radiotherapy.
Methods: Patients from a multicenter randomized controlled trial from 1987-1993 on adjuvant chemotherapy for R0-resected colorectal cancers with stage I-III disease were retrospectively allocated: cancers of the lower two-thirds of the rectum (11 cm or less from anal-verge, Group A, n = 205), of the upper-third of the rectum and rectosigmoid-junction (>11-20 cm from anal-verge, Group B, n = 142), and of the colon (>20 cm from anal-verge, Group C, n = 378). The total mesorectal excision (TME) technique had not been introduced yet. The adjuvant chemotherapy turned out to be ineffective. None of the patients received neoadjuvant or adjuvant radiotherapy.
Results: The patients had a regular follow-up (median, 8.0 years). The 5-year disease-free survival (DFS) rate was 0.54 (95%CI, 0.47-0.60) in Group A, 0.68 (95%CI, 0.60-0.75) in Group B, and 0.69 (95%CI, 0.64-0.74) in Group C. The 5-year overall survival (OS) rate was 0.64 (95%CI, 0.57-0.71) in Group A, 0.79 (95%CI, 0.71-0.85) in Group B, and 0.77 (95%CI, 0.73-0.81) in Group C. Compared with Group C, patients in Group A had a significantly worse OS (hazard ratio [HR] for death 2.10) and a worse DFS (HR for relapse/death 1.93), while patients in Group B had a similar OS (HR 1.12) and DFS (HR 1.07).
Conclusions: Adenocarcinomas of the upper third of the rectum and the rectosigmoid-junction seem to have similar prognosis as colon cancers. Even for surgeons not familiar with the TME technique, preoperative radiotherapy may be avoided for most rectosigmoid cancers above 11 cm from anal-verge.