Outcome analysis of chemotherapy duration for resected stage I-II and unresected stage III pancreatic cancer.

Abstract

375 Background: For resected early-stage pancreatic cancer, RTOG 9704 has evaluated the outcome of 3 weeks of adjuvant chemotherapy (C) followed by chemoradiation (CRT) and post-CRT C. For locally advanced pancreatic cancer, a recent literature review showed that the typical duration for induction C is between 1 and 6 months prior to CRT. The ideal duration of C prior to CRT remains unclear. This National Cancer Database (NCDB) study was performed to identify the optimal duration of C prior to CRT in patients with pancreatic cancer. Methods: The NCDB was queried for primary stage I-II, cT1-3N0-1M0, resected and stage III, cT4N0-1M0, unresected pancreatic adenocarcinoma treated with C+CRT (2004-2015). Cohorts I-II and III included stage I-II and stage III cases, respectively. In each cohort, the patients were stratified by the short (short C) and long duration (long C) of chemotherapy based on their median durations (70 and 90 days between the onset of chemotherapy and radiation for cohorts I-II and III, respectively). Baseline patient, tumor, and treatment characteristics were examined. The primary endpoint was overall survival (OS). Kaplan-Meier analysis, multivariable Cox proportional hazards method, and propensity score matching were used. Results: Among 1,577 patients, cohort I-II had 839 patients (n = 409 with short C, n = 430 with long C) and cohort III had 738 patients (n = 360 with short C, n = 378 with long C). Median follow-up was 39.5 months and 24.3 months for cohorts I-II and III, respectively. The long C group showed improved OS in the multivariable analysis in both cohort I-II (HR 0.72, p < 0.001) and cohort III (HR 0.83, p = 0.025). Using 1:1 propensity score matching, a total of 610 patients for cohort I-II and 542 patients for cohort III were matched. After matching, long C remained statistically significant for improved OS compared with short C in both cohort I-II (median OS 26.1 vs 21.9 months, p = 0.003) and cohort III (median OS 16.7 vs 14.2 months, p = 0.021). Conclusions: Our NCDB study using propensity score matched analysis showed a survival benefit in the use of longer duration chemotherapy compared to shorter duration chemotherapy for both resected stage I-II and unresected stage III pancreatic cancer.