Objective To investigate the effects of different neoadjuvant treatments on tumor regression, surgical complications and low anterior resection syndrome (LARS) in patients with rectal cancer.

Methods We included 127 patients with rectal cancer receiving neoadjuvant treatments, and they were divided into long-term concurrent chemoradiotherapy group (n=42), short-term radiotherapy+chemotherapy group (n=39) and chemotherapy group (n=46). The pathological results, clinical data and follow-up results were collected. The factors that may affect tumor regression, surgical complications and low anterior resection syndrome after rectal cancer surgery were statistically analyzed and concluded.

Results The pCR rates were 28.51%, 10.3% and 8.6% in long-term concurrent chemoradiotherapy group, short-term radiotherapy+chemotherapy group and chemotherapy group, respectively. There were 14 (33.33%), 9 (23.07%) and 10 (21.74%) patients with perioperative complications in three groups, respectively. A total of 91 patients were enrolled in the LARS study. There were 49 (53.84%) cases with LARS symptoms, including 17 (18.68%) cases with severe LARS. In three groups, there were 27 cases (including 13 cases of severe LARS), 12 cases (including 2 cases of severe LARS) and 9 cases (including 2 cases of severe LARS) of LARS symptoms, respectively.

Conclusion  Three neoadjuvant treatments have good surgical safety. Long-term concurrent chemoradiotherapy and short-term radiotherapy+chemotherapy have advantages in tumor regression, but the former is more likely to cause LARS symptoms and affect the quality of life.Comprehensive consideration is needed in the choice of clinical treatments.