Tailored selection of the interval between neoadjuvant chemoradiotherapy and surgery for locally advanced rectal cancer: analysis based on the pathologic stage or chemoradiation response

The optimal interval between neoadjuvant chemoradiotherapy (CRT) and surgery has yet to be established. Additionally, it is unknown whether patients with different pathologic stages or chemoradiation responses should undergo different intervals between CRT and surgery. Therefore, the purpose of this study was to evaluate whether this interval has a differential effect on the oncologic outcome of patients with different chemoradiation responses or pathologic stages. We performed a retrospective study of 291 rectal cancer patients who were treated with preoperative chemoradiation and surgery between March 2004 and November 2012. All patients were separated into two groups according to a 7-week treatment interval. Overall survival (OS) and disease-free survival (DFS) were compared between patients undergoing intervals that were shorter and longer than 7 weeks in the entire group and in subgroups of ypT0-2N0, ypT3-4N0 and ypT0-4N+. The recurrence patterns were also analysed in all of the subgroups. Multivariate analysis was performed to explore the clinical factors that were significantly associated with DFS, local recurrence-free survival (LRFS) and distant metastasis-free survival among patients exhibiting ypT3-4N0 and ypT0-4N+. For the ypT0-2N0 patients, the 5-year OS and DFS and the rates of local and distant recurrence were similar between the short and long interval groups. For the patients exhibiting ypT3-4N0, although no significant difference was found in OS or DFS between the short and long interval groups, the rate of local recurrence was higher in the long interval group, which was further confirmed by multivariate analysis. In the patients exhibiting ypT0-4N+, both OS and DFS were lower in the long interval group than in the short interval group. Furthermore, multivariate analysis indicated that the interval was significantly associated with DFS, especially LRFS. The interval between CRT and surgery may exert a differential effect on the prognosis of patients exhibiting different pathologic stages or chemoradiation responses. Therefore, we strongly suggest tailoring the interval between CRT and surgery in locally advanced rectal cancer.