To investigate the effect of different waiting time on pathology and prognosis of low rectal cancer after preoperative neoadjuvant chemoradiotherapy.

Seventy-seven patients who received rectal cancer surgery following neoadjuvant therapy in Jiangsu Province Hospital from January 2013 to December 2018 were retrospectively analyzed. According to the preoperative waiting time after neoadjuvant therapy, forty-three patients were divided into groupⅠ(6~8 weeks) and 34 patients in group Ⅱ(9~12 weeks). The baseline characteristics and surgical outcomes of the two groups were analyzed.

There was no significant difference in general data such as sex ratio, age, cTNM stage and CEA level between the two groups before neoadjuvant therapy (P>0.05). Postoperative pathological results showed that the positive rate of pathological lymph nodes in group Ⅱ was significantly lower than that in groupⅠ (20.6% vs. 46.5%, P=0.018). The pCR rates of group Ⅰ and group Ⅱ were 18.6% and 17.6%, respectively (χ²=0.012, P=0.914) . In group Ⅰ, 14 patients (32.6%, 14/43) had obvious regression of tumors. In group II, 13 patients (38.2%, 13/34) had obvious regression of tumors. There was no significant difference between the two groups (Z=-0.702, P=0.483) . There was no significant difference in the incidence of postoperative complications and long-term recurrence and metastasis between the two groups (P>0.05).

Extending the interval between neoadjuvant chemoradiotherapy and surgery to 9~12 weeks can further reduce the positive rate of lymph nodes compared with 6~8 weeks, but there is no significant difference in the pCR rate and the grade of tumor regression. There was no significant effect on the occurrence of short-term complications and long-term recurrence and metastasis. Delayed interval time has both advantages and disadvantages for patients, so individualized treatment strategies should be formulated according to condition.