The Impact of Adjuvant Chemotherapy on Survival in Pancreatic Cancer after Neoadjuvant Treatment

Abstract

The benefit of adjuvant chemotherapy after neoadjuvant chemotherapy and surgery in patients with non-metastatic pancreas cancer is unknown. We analyzed patients with non-metastatic pancreatic cancer using the National Cancer Database (NCDB) for patients diagnosed between 2006 and 2014. All patients received neoadjuvant chemotherapy (NAC) followed by pancreatectomy. Patients were analyzed according to whether or not they received neoadjuvant chemotherapy (NAC) only or neoadjuvant chemotherapy plus adjuvant chemotherapy (NAC + AC). The primary endpoint was OS from the time of diagnosis. Propensity-score matching was used to account for differences in baseline characteristics. Kaplan-Meier and Cox proportional hazard modeling were used to analyze OS. A total of 2,517 patients were included for analysis; 1,820 in the NAC group, and 697 in the NAC + AC group. Neoadjuvant radiation was received by 51% of patients. After propensity score matching, well-balanced groups of 267 patients were analyzed. After median follow-up of 21.1 months in the NAC group, and 23.9 months in the NAC + AC group, there was a statistically significant improvement in median OS for those treated with NAC + AC (31.1 months, 95% CI: 26.1 – 37.9 months), compared to those who received NAC only (25.6 months, 95% CI: 22.1 – 29.1 months, p=0.014). The 1-year, 3-year, and 5-year OS rates for the NAC + AC group were 90.3%, 45.9%, and 18.9%, respectively. For the NAC group, the 1, 3, and 5-year OS rates were 82.5%, 34.5%, and 15.7%, respectively. After shared frailty Cox UVA, the addition of AC to NAC was found to decrease the risk of death (HR 0.74, p=0.01). On subgroup analysis, patients with ypN+ had improved OS with the addition of AC (HR 0.71, p=0.024), while those with ypN0 did not (HR 0.78, p=0.17). In patients with non-metastatic pancreatic cancer treated with neoadjuvant chemotherapy, surgery, and adjuvant chemotherapy (NAC + AC), there was a statistically significant improvement in OS compared to those treated with neoadjuvant chemotherapy and surgery alone (NAC). This improvement in OS was only seen in ypN+ patients on subgroup analysis.