Efficacy of S-1 in 2L chemotherapy after nab-paclitaxel plus gemcitabine for patients with advanced pancreatic cancer

Purpose Second-line (2L) chemotherapy is important option to improve survival. However, the efficacy of S-1 after nab-paclitaxel plus gemcitabine (AG) for advanced pancreatic cancer (APC) remained unclear. Thus, we retrospectively investigated the clinical impact of S-1 after AG. Methods From January 2015 to July 2018, 37 patients with APC underwent AG as a first-line chemotherapy at our institute. Of these, 14 patients (38%) had S-1 as a 2L chemotherapy after AG (S-1 group), 3 patients (8%) received modified FOLFIRINOX, 1 patient (3%) continued GEM and 1 patient (3%) underwent GEM accompanied carbon ion beam, respectively. 18 patients (49%) did not have any 2L chemotherapy (BSC group). The clinical features were retrospectively compared between the two groups. Prognostic factors for residual survival time (RS) were analyzed using the Cox proportional hazards model. Results The introduction rates of 2L chemotherapy was 51%. Of these, S-1 monotherapy was mostly used (74%). Disease control rate and progression-free survival were 57.1% (95% CI, 32.6-78.6%) and 2.8 months (95% CI, 1.9-5.6 months), respectively. Median RS (MRS) in the S-1 group was 5.2 months (95%CI, 3.8-5.9 months), whereas the MRS in the BSC group was 2.4 months (95%CI, 0.9-3.3 months); this difference was statistically significant (hazard ratio, 0.33, P = 0.005). Median overall survival time (MST) in the S-1 group was 12.3 months (95%CI, 6.2-15.0 months), whereas the MST in the BSC group was 5.0 months (95%CI, 3.4-6.8 months); this difference was statistically significant (hazard ratio 0.26, P = 0.001). In multivariate analysis, the efficacy of S-1 in 2L chemotherapy for RS was identified as well as age ( Conclusions RS and overall survival in S-1 group compared with BSC group were prolonged 2.8 and 7.3 months, respectively. The introduction of S-1 after AG might improve the prognosis of patients with APC.