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Comparison of adjuvant chemotherapy, chemoradiation, and chemotherapy followed by chemoradiation for resected stage I-II pancreatic cancer.

372 Background: Prior National Cancer Database (NCDB) studies have demonstrated an overall survival (OS) benefit for adjuvant concurrent chemoradiation (CRT) compared to chemotherapy alone. Given the more recent adoption of postoperative chemotherapy followed by concurrent chemoradiation (C+CRT), this NCDB analysis evaluates the clinical outcomes of C+CRT compared to CRT alone or adjuvant chemotherapy alone (C) for resected pancreatic cancer. Methods: The NCDB was queried for primary stage I-II, cT1-3N0-1M0, resected pancreatic adenocarcinoma treated with adjuvant C, CRT, or C+CRT (2004-2015). Patients treated with C+CRT were compared with those treated with C (cohort C) or with CRT (cohort CRT). The primary endpoint was overall survival (OS). Baseline patient, tumor, and treatment characteristics were examined. Kaplan-Meier analysis, multivariable Cox proportional hazards method, forest plot, and propensity score matching were used. Results: Among 5667 patients (n = 3031 for C, n = 1307 for CRT, n = 1329 for C+CRT), median follow-up was 34.7 months, 45.2 months, and 39.7 months for the C, CRT, and C+CRT cohorts, respectively. In the multivariable analysis for all patients, C (HR 1.31, p < 0.001) and CRT (HR 1.24, p < 0.001) were associated with worse mortality compared to C+CRT. Treatment interactions were seen among pathologically node positive disease. C+CRT was favored in 1-3 (HR 0.74, p < 0.001) and 4+ (HR 0.75, p < 0.001) positive lymph node disease when compared to C or CRT alone, but none of the treatment options were significantly favored in node negative disease (HR 0.96, p = 0.67). Using 1:1 propensity score matching, 2152 patients for cohort C and 1774 patients for cohort CRT were matched. C+CRT remained significant for improved OS for both cohort C (median OS 23.3 vs 20.0 months, p < 0.001) and cohort CRT (median OS 23.4 vs 20.8 months, p < 0.001). Conclusions: This NCDB study using propensity score matched analysis demonstrates an OS benefit for C+CRT compared to C or CRT alone following surgical resection of pancreatic cancer. Most of this benefit is in patients with positive lymph nodes.