Neoadjuvant chemoradiotherapy versus neoadjuvant chemotherapy alone for patients with locally advanced rectal cancer: a propensity-score-matched analysis combined with SEER validation

BACKGROUND: Neoadjuvant therapy followed by radical surgery is recommended for locally advanced rectal cancer (LARC). But radiotherapy can cause potential adverse effects. The therapeutic outcomes, postoperative survival and relapse rates between neoadjuvant chemotherapy (N-CT) and neoadjuvant chemoradiotherapy (N-CRT) patients have rarely been studied. METHODS: From February 2012 to April 2015, patients with LARC who underwent N-CT or N-CRT followed by radical surgery at our center were included. Pathologic response, surgical outcomes, postoperative complications and survival outcomes (including overall survival [OS], disease-free survival [DFS], cancer-specific survival [CSS] and locoregional recurrence-free survival [LRFS]) were analyzed and compared. Concurrently, the Surveillance, Epidemiology, and End Results Program (SEER) database was used to compare OS in an external source. RESULTS: A total of 256 patients were input into the propensity score-matching (PSM) analysis, and 104 pairs remained after PSM. After PSM, the baseline data were well matched and there was a significantly lower tumor regression grade (TRG) (P < 0.001), more postoperative complications (P = 0.009) (especially anastomotic fistula, P = 0.003) and a longer median hospital stay (P = 0.049) in the N-CRT group than in the N-CT group. No significant difference was observed in OS (P = 0.737), DFS (P = 0.580), CSS (P = 0.920) or LRFS (P = 0.086) between the N-CRT group and the N-CT group. In the SEER database, patients who received N-CT had similar OS in both TNM II (P = 0.315) and TNM III stages (P = 0.090) as those who received N-CRT. CONCLUSION: N-CT conferred similar survival benefits but caused fewer complications than N-CRT. Thus, it could be an alternative treatment of LARC. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00432-023-04779-y.