Association of decline in serum Ca19-9 after neoadjuvant therapy with improved survival among borderline resectable pancreatic cancer patients.

e15082 Background: Serum Ca19-9 (19-9) decline in response to therapy has been associated with an increased overall survival in metastatic pancreatic cancer patients (pts). However, the prognostic value of a 19-9 decline after neoadjuvant therapy in pts with localized disease is less well defined. Methods: We evaluated 73 pts with NCCN defined BRPC who received neoadjuvant therapy with induction chemotherapy (CRX) followed by chemoradiation (CRT). Staging with CT and 19-9 was obtained at three defined time points: baseline (bilirubin normal), after CRX, and following CRT (pre-surgical). Change in 19-9 (δ19-9) was defined as: (baseline 19-9- pre-surgical 19-9)/baseline 19-9. δ19-9 was classified as: absent (δ19-9<0) or minimal (0 <δ19-9<0.25), low (0.25<δ19-9<0.50), moderate (0.50<δ19-9<0.75), high (δ19-9> 0.75). Results: Of the 73 pts, 20 pts had normal/undetectable 19-9 and were excluded from the analysis. Of the remaining 53 pts, mean 19-9 levels at baseline, after CRX, and after CRT were 956, 164, and 139 U/mL, respectively. The mean change in 19-9 after CRX was 44%. Changes in 19-9 after CRX correlated with continued decline in 19-9 after CRT (Spearman rho = 0.81, p<0.001). δ19-9 was high in 38 (71%), moderate in 9 (17%), min/low in 1 (2%), and absent in 5 (9%). Of the 53 pts, 49 (92%) were considered for surgery after neoadjuvant therapy and 38 (72%) underwent pancreatectomy. In a multivariate logistic regression, higher δ19-9 was associated with a 5.4 fold increased odds of completing all neoadjuvant therapy including surgery as compared to pts with no change in 19-9 (absent δ19-9; HR 5.4, p=0.12). Patients with absent δ19-9 had a worse overall survival than pts with minimal to high δ19-9 (median survival 11.5 mo vs. 30.1 mo, p = 0.0002). In a multivariate Cox proportional hazard, a decline in pre-surgical 19-9 from baseline was associated with improved survival (HR 0.21, p =0.02). Conclusions: Following neoadjuvant therapy, a decline in 19-9 is associated with surgical resection and improved overall survival. An increase in 19-9 above baseline (the absent δ19-9 group) prior to surgery is a poor prognostic marker and such patients may benefit from additional systemic therapy.