Neoadjuvant Therapy for Rectal Cancer: The Impact of Longer Interval Between Chemoradiation and Surgery

Purpose The aim of this study was to determine the effect of a longer interval between neoadjuvant chemoradiation and surgery on perioperative morbidity and oncologic outcomes. Methods A colorectal cancer database was queried for clinical stage II and III rectal cancer patients undergoing neoadjuvant chemoradiation followed by proctectomy between 1997 and 2007. The neoadjuvant regimen consisted of long course external beam radiation and 5-fluorouracil chemotherapy. Patients with inflammatory bowel disease, hereditary cancer, extracolonic malignancy, urgent surgery, or non-validated treatment dates were excluded. Patients were divided into two groups according to the interval between chemoradiation and surgery (< 8 and >= 8 weeks). Perioperative complications and oncologic outcomes were compared. Results One hundred seventy-seven patients were included. Groups were comparable with respect to demographics, tumor, and treatment characteristics. Perioperative complications were not affected by the interval between chemoradiation and surgery. Patients undergoing surgery >= 8 weeks after chemoradiation experienced a significant improvement in pathologic complete response rate (30.8% vs. 16.5%, p=0.03) and had decreased 3-year local recurrence rate (1.2% vs. 10.5%, p=0.04). A Cox regression analysis was performed to assess the compounding effect of a complete pathologic response on oncologic outcome. A longer interval correlated with less local recurrence, although statistical significance was not reached (p=0.07). Conclusion An interval between chemoradiation and surgery >= 8 weeks is safe and is associated with a higher rate of pathologic complete response and decreased local recurrence.