A pathologic complete response to preoperative chemoradiation is associated with lower local recurrence and improved survival in rectal cancer patients treated by mesorectal excision.

PURPOSE: Preoperative chemoradiation reduces tumor size and nodal metastasis in patients with rectal cancer. Tumor downstaging has been associated with an increased probability of a sphincter-saving procedure and with improved local control. However, pathologic complete response to chemoradiation has not been correlated with local control and patient survival. We studied the prognostic value of pathologic complete response to preoperative chemoradiation in rectal cancer patients.
METHODS: We have prospectively followed up 168 consecutive patients with ultrasound Stages II (46) and III (122) rectal cancer treated by preoperative chemoradiation followed by radical resection with mesorectal excision; 161 had a curative resection. Recurrence and survival were compared with tumor characteristics and pathologic complete response. Average follow-up was 37 months.
RESULTS: Tumor downstaging occurred in 97 (58 percent) patients, including 21 (13 percent) patients who had a pathologic complete response. None of the clinical or pathologic variables was associated with pathologic complete response. The estimated 5-year rate of local recurrence was 5 percent; of distant metastasis, 14 percent. None of the patients with pathologic complete response has developed disease recurrence. We found no difference in survival among patients with pathologic Stages I, II, or III tumors.
CONCLUSIONS: A pathologic complete response to preoperative chemoradiation is associated with improved local control and patient survival. For patients without pathologic complete response, the pathology stage does not have prognostic significance.