Adjuvant Chemotherapy After Neoadjuvant Chemotherapy for Pancreatic Cancer is Associated with Improved Survival for Patients with Low-Risk Pathology

Background: With limited evidence, the benefit of adjuvant chemotherapy (AT) after completion of neoadjuvant chemotherapy (NT) and surgical resection for patients with pancreatic adenocarcinoma is debated. Guidelines recommend 6 months of AT for patients receiving NT. However, the patient-derived benefit from additional AT remains unknown. Methods: The National Cancer Database from 2006 to 2015 was used to identify patients undergoing NT. The chi-square test and multivariable logistic regression were used to identify differences between those receiving only NT and those receiving NT and AT. Survival analysis using the Kaplan-Meier method and the Cox proportional hazard ratio model was applied to the entire cohort and to subgroups with differing lymph node ratios (LNRs), tumor sizes, grades, and surgical margin statuses. Results: Of the 3897 patients who received NT, 36.7 % received additional AT. Analysis of the entire cohort showed that associated survival was significantly improved with NT and AT compared with NT alone (hazard ratio [HR], 0.83; p < 0.001). In the subgroup analysis, the survival benefit of additional AT remained significant for those with negative nodal disease, an LNR lower than 0.15, low-grade histology, and negative margin status. Overall survival did not differ between those receiving NT only and those receiving NT and AT in the group with an LNR of 0.15 or higher, high-grade histology, and positive margins. Conclusion: This study identified an increasing trend in the use of AT after NT and showed an associated survival benefit for subgroups with low-risk pathologic features. These results suggest that the addition of AT after NT likely beneficial for these subgroups.