Sites of local recurrence after surgery, with or without chemotherapy, for rectal cancer: implications for radiotherapy field design.

ABSTRACT

PURPOSE: To examine the sites of pelvic recurrence in patients with rectal cancer previously untreated with radiotherapy to determine the relative frequency and location of recurrence within the pelvis. METHODS AND MATERIALS The records of patients with locally recurrent rectal cancer referred to three radiation oncology departments between 1984 and 1997 were reviewed. The data collected included the date and type of the initial resection and the pathologic findings. The site of recurrence within the pelvis, presence of metastasis, and date of recurrence were documented. RESULTS: A total of 269 patients were included. Tumor had invaded through the muscularis in 74% and involved other organs in 9%. Fifty-two percent of patients were node positive at initial surgery. The median time to local recurrence from surgery was 18 months (range 15-20) and from local recurrence to death was 14 months (range 12-17). Both the initial tumor stage and the resection type influenced the recurrence location within the pelvis (p <0.01). T4 tumors comprised only 9% of initial T stage tumors but accounted for 38% of anterior central pelvic recurrences (p <0.01). All perineal recurrences occurred after abdominoperineal resection. The sites of recurrence within the pelvis were the posterior central pelvis (47%) and anastomotic (21%). CONCLUSION: If those patients with T4 tumors at presentation were excluded, 89% had local recurrence at, or posterior to, the anastomosis. Furthermore, if we exclude both patients who underwent abdominoperineal resection and those with T4 tumors at presentation, the rate increases to 93%. The rate of recurrence anteriorly (7%) does not justify routine radiation of the anterior pelvis beyond that required to adequately cover the anastomotic site.