CA19-9 Change During Neoadjuvant Therapy May Guide the Need for Additional Adjuvant Therapy Following Resected Pancreatic Cancer

Background Neoadjuvant therapy (NAT) is increasingly utilized for pancreatic cancer, however the added benefit of adjuvant therapy (AT) in this setting is unknown. We hypothesized that the magnitude of CA19-9 response to NAT can guide the need for further AT in resected pancreatic cancer. Methods CA19-9 secretors who received NAT for pancreatic cancer during 2008–2016 at a single institution were analyzed and CA19-9 response (difference between pre- and post-NAT values) was measured. Kaplan–Meier estimators and Cox proportional hazard ratio models were used to determine the optimal CA19-9 response at which AT ceases to confer any additional survival benefit after NAT. Results A total of 241 patients (mean age 65.4 years, 50% female) with complete CA19-9 data who underwent NAT followed by resection were analyzed. In a cohort of patients ( n = 78) in whom CA19-9 normalized with a decrease > 50% after NAT (optimal responders), AT was not associated with additional survival benefit (40.6 vs. 39.0 months, p = 0.815). Conversely, in the cohort of patients ( n = 163) in whom NAT was not associated with normalization and a decrease of ≤ 50% in CA19-9 (suboptimal responders), receipt of AT was associated with a survival benefit (34.5 vs. 19.1 months, p < 0.001) following NAT. A Cox proportional hazards model confirmed CA19-9 normalization and decrease > 50% during NAT to predict no additional survival benefit from AT. Conclusions The magnitude of CA19-9 response to NAT may predict the need for further AT in resected pancreatic cancer. Prospective studies are needed to elucidate the optimal interplay of NAT and AT in pancreatic cancer.