Long-Term Survival Analysis of Neoadjuvant Chemoradiotherapy Versus Adjuvant Chemoradiotherapy for Locally Advanced Low Rectal Cancer.

Purpose: To compare the long-term survival of patients with locally advanced low rectal cancer (LALRC), receiving neoadjuvant chemoradiotherapy (NCRT) versus adjuvant chemoradiotherapy (ACRT).

Methods And Materials: This retrospective observational study included 1169 patients with LALRC (Stage II/III disease located ≤ 5 cm from the anal verge) who underwent diagnosis and treatment at Fudan University Shanghai Cancer Center from February 2006 to March 2021. In Stage II/III low rectal cancer patients, one-to-one matched pairs were created from the ACRT and NCRT groups using propensity score matching (PSM) based on baseline characteristics. OS and DFS were evaluated using the Kaplan-Meier method alongside the univariate Cox regression model.

Results: In Stage II patients, 65 received ACRT and 107 received NCRT. For Stage III, 282 received ACRT and 715 received NCRT. After PSM, 45 paired Stage II patients and 243 paired Stage III patients were selected. In Stage II patients, there was no significant difference in OS and DFS between the groups. For Stage III, the 5- and 10-year OS rates were 79.61% and 77.67% in the NCRT group, compared to 61.08% and 44.57% in the ACRT group (p < 0.001). The 5- and 10-year DFS rates were 69.93% and 65.26% in the NCRT group, versus 48.07% and 40.77% in the ACRT group (p < 0.001). Additionally, in Stage III patients, NCRT was associated with a significant reduction in the risk of death and recurrence compared to ACRT (OS: HR = 0.47, p = 0.0001; DFS: HR = 0.55, p = 0.0001).

Conclusion: For patients with Stage III low rectal cancer, NCRT significantly improved the long-term DFS rate and OS rate, in comparison to adjuvant chemoradiotherapy.