Time to Adjuvant Chemotherapy and Survival Outcomes Among Patients With Stage 2 to 3 Rectal Cancer Treated With Preoperative Chemoradiation

Abstract

BackgroundPrevious studies have evaluated the impact of time to adjuvant chemotherapy (AC) on survival in early-stage colon cancer. However, the optimal time to adjuvant chemotherapy (TTAC) in rectal cancer remains unclear. The objective of this study was to identify an optimal TTAC and determine its prognostic effect in stage 2 to 3 rectal cancer. MethodsPatients with stage 2 to 3 rectal cancer treated with preoperative chemoradiation and postoperative AC between 1999 and 2008 were included. Predetermined time points of 4, 6, 8, and 12 weeks from date of surgery were analyzed. Cut-point analysis was then used to determine an optimal TTAC, and overall survival at the identified cut-point was evaluated. ResultsA total of 328 eligible patients were identified with a median age of 61 years (range 22-85 years), 70% male, and 75% stage 3 disease. The median TTAC was 7.0 weeks. Initiation of AC at 6 weeks from date of surgery was associated with a significant survival benefit (hazard ratio 0.52, 95% confidence interval 0.31-0.90, P = .017), while no significant association was seen at 4, 8 or 12 weeks (P > .05). The cut-point analysis identified an optimal TTAC of 5.6 weeks association with improved survival compared to those with a TTAC greater than 5.6 weeks (hazard ratio 0.42, 95% confidence interval 0.22-0.82, P = .0087). This cut-point was also found to be a significant prognostic factor in multivariable analysis (P = .04) adjusted for Eastern Cooperative Oncology Group performance status, age, gender, stage, margin status, and grade. ConclusionsThis study suggests that initiation of AC within an earlier time frame is associated with improved overall survival.