Use of Neoadjuvant Chemotherapy in the Treatment of Locally Advanced Rectal Cancer.

BACKGROUND: Current treatment for locally advanced rectal cancer includes neoadjuvant chemoradiation followed by surgery and adjuvant chemotherapy. With neoadjuvant chemotherapy (NC), both chemoradiation and chemotherapy are given in the neoadjuvant setting. This study aims to assess patterns of NC utilization and differences in treatment response compared with standard treatment at our institution. MATERIALS AND METHODS: We performed a retrospective review of patients treated for stage II-III rectal cancer at our institution between 2008 and 2018, examining patient demographics, tumor characteristics, and treatment modality. The primary outcome of interest was complete response (CR) to treatment, including both pathologic and clinical CR. RESULTS: Of 184 patients, 134 (72.8%) received standard therapy, and 50 (27.2%) received NC. In the standard treatment group, 70.1% were node positive, and 9.0% had T4-disease, compared with 92.0% and 26.0% in the NC group, respectively (both P < 0.01). NC utilization increased over time, with 3.4% of patients receiving NC between 2008 and 2012, compared with 48.5% in 2013-2018 (P < 0.01). CR was achieved in 19.4% versus 34.0% (P < 0.01) of patients in standard versus NC groups. With multivariate analysis, NC (odds ratio = 3.02 [95% confidence interval 1.37-6.67], P = 0.01) was associated with increased likelihood of achieving CR, whereas higher T-stage was associated with decreased likelihood of CR (for cT4, odds ratio = 0.06 [95% confidence interval 0.01-0.56], P = 0.01). CONCLUSIONS: Use of NC was increasingly used at our institution from 2008 to 2018. Patients who received NC achieved higher rates of CR compared with those undergoing standard therapy, despite having more advanced disease. These data support trends from other institutions and provides rationale for further study regarding use of NC for locally advanced rectal cancer.