Impact of timing of adjuvant chemotherapy initiation on survival in pancreatic adenocarcinoma.
355 Background: Pancreatic adenocarcinoma (PDAC) is now the third leading cause of cancer death. Surgical resection followed by adjuvant chemotherapy has been the standard of care. Due to the significant risk of morbidity following pancreatic surgery, initiation of adjuvant chemotherapy is often delayed. Prior prospective adjuvant trials have suggested that adjuvant therapy can be initiated as late as 12 weeks without detriment, but data regarding the effectiveness of beginning adjuvant therapy beyond that time remains unknown. Methods: We retrospectivelyreviewed data from the National Cancer Data Base (2004-2014) and included adult patients (pts) with PDAC with pathologic stage I-IIB who underwent surgical resection with curative intent. The primary outcome was overall survival (OS) based on time to adjuvant chemotherapy post-surgery as defined by postoperative weeks. Data were analyzed using Cox proportional hazard model and Kaplan-Meier survival curves. Results: 5279 pts. had surgery alone and 4,537 pts. received adjuvant chemotherapy. The median age was 64 years. 52% were male, 88% were white, 46% were treated at comprehensive community cancer centers. The primary surgical approach was whipple procedure in 61% of pts. 63% pts. received single agent chemotherapy and the mean time from surgery to chemotherapy was 61 days. Adjuvant chemotherapy was associated with improved OS irrespective of disease stage compared to those undergoing surgery alone (median OS for surgery alone 14 months vs adjuvant chemotherapy 21 months, p < 0.001). Cox proportional hazard model controlling for stage, surgical technique, lymph node dissection and margin status revealed improved OS in pts. receiving adjuvant chemotherapy. No significant differences in OS were seen for pts. starting adjuvant chemotherapy at 3, 6, 9, 12, 16, 20 or 24 weeks after surgical resection. Conclusions: Current guidelines recommend initiation of adjuvant chemotherapy prior to 12 weeks after pancreatic resection. Initiating adjuvant chemotherapy even up to six months post-operatively improves OS compared to those undergoing surgery alone. Our data supports the use of adjuvant chemotherapy if indicated regardless of time of surgery.