Efficacy of S-1 monotherapy for older patients with unresectable pancreatic cancer: A retrospective cohort study.

Objectives: Pancreatic cancer is a fatal malignancy that frequently occurs in older patients. However, limited evidence is available on the effects of chemotherapy on older patients with unresectable pancreatic cancer. Here we explored the efficacy of S-1, an oral fluorouracil drug, compared with gemcitabine, as first-line chemotherapy.

Materials And Methods: We conducted a retrospective cohort study of patients with unresectable pancreatic cancer aged ≥75 years. For this purpose, we used the claims and master databases of the Fukuoka Prefecture Wide-Area Association of Latter-Stage Elderly Healthcare between April 1, 2010 to March 31, 2017. According to first-line chemotherapy, we divided patients into gemcitabine and S-1 groups to compare three-year survival from the date of diagnosis and time to second-line chemotherapy as a surrogate indicator of progression-free survival. We analyzed the data using multivariate Cox proportional hazards method.

Results: The study comprised 680 patients, of which 92.5% (N = 629) died within three years of diagnosis. The S-1 group had a significantly lower risk of death within three years of diagnosis (hazard ratio (HR) 0.695, 95% CI: 0. 588-0. 821, p < .001). There were no significant differences (HR 0.968, 95% CI: 0.708-1.324, p = .838) in time to second-line chemotherapy. Two sensitivity analyses excluding study subjects who received radiation therapy or second-line chemotherapy yielded consistent results (HR 0.746, 95% CI: 0.622-0.895, p = .002, HR 0.628, 95% CI: 0. 509-0.776, p < .001, respectively).

Conclusion: S-1 can serve as a first-line chemotherapeutic option of patients aged ≥75 years with unresectable pancreatic cancer.