Abstract
This study compared long-term population-based survival outcomes of preoperative and postoperative radiotherapy (RT) approaches in rectal cancer. Patients with stage II-III rectal cancer between 1998 and 2013 were identified using the Surveillance, Epidemiology, and End Results database. Overall survival (OS) and disease-specific survival (DSS) rates were estimated in propensity-matched study population according to the use of RT. Among the 28,320 eligible patients, a total of 18,400 patients were identified from propensity score matching process balancing the distribution of prognostic covariates. The 10-year OS and DSS rates were higher in patients with preoperative RT than the postoperative group (51.6% vs. 49.8% with P < 0.001, and 65.4% vs. 64.8% with P = 0.037, respectively). However, in multivariate analysis, selection of combined RT sequence did not affect the survival (hazard ratio [HR] 1.04 and 95% confidence interval [CI] 0.98−1.10 for OS; HR 0.97 and 95% CI 0.90−1.05 for DSS). Regarding hazard rate functions of cancer-specific mortality, the overall time-course risks after preoperative and postoperative RT were comparable. This study provides additional insight into the long-term prognostic implications of the two RT strategies, suggesting that the sequence of RT does not lead to differential survival in stage II-III rectal cancer.
Highlights
According to the recent cancer statistics, colorectal cancer is the 3rd most common cancer in the United States[1]
We evaluated long-term survival outcomes of stage II-III rectal cancer patients who underwent preoperative or postoperative RT
Use of RT prior to radical surgery was associated with improved Overall survival (OS) and disease-specific survival (DSS) in univariate Kaplan-Meier analysis
Summary
According to the recent cancer statistics, colorectal cancer is the 3rd most common cancer in the United States[1]. Given that the Dutch trials demonstrated improved local control with neoadjuvant RT7,8, three phase III randomized controlled trials, including the German CAO/ARO/AIO-94, National Surgical Adjuvant Breast and Bowel Project (NSABP) R-03, and a Korean study, compared pre- and postoperative use of RT9–11. Despite widespread use of the preoperative approach, a recent report from the National Cancer Data Base stated that approximately only one-half of stage II-III rectal cancer patients underwent RT before surgery in the United States[14]. We used the Surveillance, Epidemiology, and End Results (SEER) program, a nation-wide cancer database from the United States[15], to evaluate the potential of improved survival with preoperative RT in comparison with postoperative treatment in stage II-III rectal cancer. Our matched comparison analysis of long-term survival outcomes provides additional knowledge for optimizing the sequence of RT combined with surgery in locally advanced rectal cancer
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