Temporal trends and disease characteristics associated with total neoadjuvant therapy (TNT) usage.

642Background: Neoadjuvant chemoradiotherapy (nCRT) followed by resection and postoperative multi-agent chemotherapy (maChT) is the standard of care for locally advanced rectal cancer (LARC). Using this approach, maChT administration is delayed several months, leading to concern for high rates of distant failure. To reduce the rate of systemic failure, a novel treatment approach known as total neoadjuvant therapy (TNT) has been increasingly employed, in which patients receive both maChT and nCRT prior to resection. We utilized the National Cancer Database (NCDB) to examine temporal trends in TNT usage, as well, as any potential effect on survival. Methods: We queried the NCDB for patients diagnosed with LARC (Stage II-III) from 2004–2015 treated with nCRT or TNT. TNT was defined as maChT initiated ≥ 90 days prior to the start of nCRT. Overall survival (OS) was calculated from the date of diagnosis to the date of last contact or death using Kaplan Meier curves to present the cumulative probability of survi...