LAUSR

e15597 Background: Patients with locally advanced rectal cancer (LARC) typically receive chemoradiation prior to surgery, followed by adjuvant chemotherapy (standard). Recently there has been a growing trend toward total neoadjuvant therapy (TNT), in which all chemotherapy is given in the neoadjuvant setting, having the advantage of higher chemotherapy completion rates. Data exploring adherence to both standard therapy and TNT within a vulnerable, underserved population is lacking. Within our safety-net hospital, we determined the chemotherapy completion rates for LARC patients who received TNT vs standard treatment. We also compared two populations within the standard treatment group- those who received all doses of prescribed adjuvant chemotherapy (AC) and those who did not. Methods: A retrospective chart review was performed for all patients with LARC (stage II or III) presenting to Los Angeles County + USC Medical Center from 2015 to 2020. Patients who progressed prior to receiving their first dose of chemotherapy and patients lost to follow-up were excluded. Patient demographics, stage, neoadjuvant/adjuvant treatment, operative characteristics, and postoperative course were abstracted. T-tests and Wilcoxon rank-sum tests were used to compare means and medians, respectively; chi-squared tests were used to compare categorical variables. Results: 67 patients were included- 59 in the standard group and 8 in the TNT group. Mean follow-up was 30 months. All patients in the TNT group completed neoadjuvant chemotherapy. In the standard treatment group, the overall AC completion rate was 81% (n = 48) (Complete Group). 19% (n = 11) did not receive all prescribed doses of AC (Incomplete Group). Compared to patients in the Incomplete Group, patients in the Complete Group were significantly older (mean age 55 vs 48, p = 0.017), had a shorter mean time interval from surgery to initiation of AC (9 weeks vs 13 weeks, p = 0.016), and were less likely to experience a delay in receiving AC > 90 days (15% vs 46%, p = 0.022). In total, 12 patients (20%) in the standard group experienced a delay in AC, of which six (50%) were due to anastomotic leak and/or pelvic abscess. Three of those patients who experienced a delay (25%) required either drain placement or re-operation to address their complication. More patients in the Complete Group went on to have their temporary stomas reversed compared to those in the Incomplete Group (94% vs 70%, p = 0.031). Conclusions: While this population had a high AC completion rate, a meaningful proportion of all patients (though more in the Incomplete Group) experienced a delay in AC > 90 days, with surgical complications responsible for the delay in half of these patients. In contrast, all patients who received TNT completed neoadjuvant chemotherapy. TNT may be a reasonable alternative to reduce therapy delays and further improve chemotherapy completion rates in an underserved population.