Neutropenia as a prognostic factor and safety of second-line therapy with S-1 for advanced or recurrent pancreatic cancer.

The aim of this retrospective study was to investigate the safety of S-1 as second-line therapy and to evaluate the association between neutropenia occurring during first-line gemcitabine (GEM) therapy and survival for advanced or recurrent pancreatic cancer (APC). Between January, 2010 and December, 2014, 123 APC patients received chemotherapy at the Ogaki Municipal Hospital (Ogaki, Japan). Of those, 37 received GEM as first-line and S-1 as a second-line therapy (GEM→S-1 group). A further 60 patients received GEM as first-line therapy, but did not receive second-line therapy (GEM group). The median overall survival in the GEM→S-1 (n=37) and GEM (n=60) groups was 323 days [95% confidence interval (CI): 138-218.9 days] and 172 days (95% CI: 105-184.4 days), respectively (P=0.0004). The median overall survival in the mild (grade ≤2; n=63) and severe (grade ≥3; n=34) neutropenia groups was 178 days (95% CI: 182-275 days) and 330 days (95% CI: 297-514 days), respectively (log-rank test, P=0.0023). The severe non-haematological toxicities associated with S-1 as second-line therapy were nausea (2.7%) and hand-foot syndrome (2.7%). Second-line S-1 treatment was discontinued due to adverse events in 5.4% (2/37) of the cases. In conclusion, neutropenia occurring during GEM therapy administered as first-line treatment to APC patients was strongly associated with a better prognosis. S-1 therapy as second-line treatment was associated with a low incidence of severe adverse events and the patients were able to successfully continue treatment.