Response to preoperative chemoradiation increases the use of sphincter-preserving surgery in patients with locally advanced low rectal carcinoma

BACKGROUND. Although controversial, some believe that preoperative chemoradiation increases the use of sphincter-preserving surgery, in low rectal carcinoma patients. This article investigates the relationship between objective tumor response and sphincter preservation in low rectal carcinoma patients. METHODS. The authors reviewed the records of 238 patients with T3 or T4 low rectal carcinoma (≤ 6 cm from the anal verge) who underwent preoperative pelvic chemoradiation (45 Gy/25 fractions/5 weeks, n = 182 or 52.5 Gy/30 fractions/5 weeks, n = 56 with continuous infusion 5-fluorouracil at 300 mg/m², Monday to Friday) followed by mesorectal (n = 223) or local excision (n = 15). A logistic regression analysis was used to analyze the influence of objective tumor response (defined as complete clinical response) and other prognostic factors on sphincter preservation. Because degrees of partial response could not be objectively defined retrospectively, the influence of partial response on sphincter preservation could not be evaluated. RESULTS. Overall, 49% of patients (117 of 238) had sphincter-preserving surgery. The clinical complete response rate was 47%. Independent predictors of sphincter preservation included the year of surgery, tumor distance from the anal verge, circumferential tumor involvement, and response to chemoradiation. The sphincter preservation rate increased over the period of the study (from 28% [December 1989 to December 1992] to 44% [January 1993 to December 1996] to 67% [January 1997 to December 2000]). The difference in the rates of sphincter preservation according to response was most striking among patients with tumors 3 cm or less from the anal verge (44% vs. 22%, P = 0.01). The pelvic disease recurrence rate among patients undergoing sphincter-preserving surgery has been less than 10% since January 1993 and was not statistically different between the groups treated from January 1993 to December 1996 and from January 1997 to December 2000. CONCLUSIONS. There has been an increase in the use of sphincter-preserving surgery without an increase in pelvic disease recurrence over the past decade. Although not necessary for sphincter preservation, clinical response to preoperative chemoradiation independently contributed to sphincter-preserving surgery, particularly in patients with low rectal tumors.