Impact of renal function on the efficacy and safety of S-1 with concurrent radiotherapy for locally advanced pancreatic cancer.

Abstract

301 Background: S-1 is an oral agent consisting of a mixture of tegafur which is a prodrug of 5-fluorouracil (5-FU), 5-chloro-2,4-dihydroxypyrimidine (DHP) and potassium oxonate. Serum concentration of 5-FU increases in case of renal dysfunction due to decrease of DHP excretion into urine. The aim of this study was to evaluate the influence of renal function to the efficacy and safety of S-1 with concurrent radiotherapy (RT) for locally advanced pancreatic cancer (LAPC). Methods: This study was an integrated exploratory analysis of JCOG1106 and LAPC- S1RT, in which pts with LAPC received RT (50.4Gy/28 fr over 5.5 weeks) and concurrent S-1 (40 mg/m2/dose, bid. on the day of irradiation). Eligibility criteria for this study were pts who received both irradiation and S-1 at least once without induction chemotherapy, and who had creatinine clearance (CCr) ≥ 50 ml/min at the time of registration. We assigned pts into high (≥ 80 ml/min) and low (< 80 ml/min) CCr groups. The primary endpoint was the incidence of ≥ Grade 3 adverse reactions (ARs). Secondary endpoints were the incidence of ≥ Grade 2 gastrointestinal ARs (GI-ARs) defined as anorexia, nausea, vomiting, diarrhea and mucositis oral, relative dose intensity of S-1, CA19-9 response, progression-free survival, and overall survival. Results: Fifty and 59 pts were included in this study from JCOG1106 and LAPC-S1RT, respectively. Median age was 65 years old (range: 31–80), and 57 pts were male. Median CCr was 80.4 ml/min. High CCr group included 57 pts and the median was 97.5 ml/min (range 80.0–194.6), and low CCr group included 52 pts and the median was 64.4 ml/min (range 50.0–78.3). Low CCr group tended to have more ≥ Grade 3 ARs and ≥ Grade 2 GI-ARs compared to high CCr group (30.8% vs. 15.8% and 51.9% vs. 36.8%). However, no evident tendencies were observed in other secondary endpoints. Multivariable analysis showed risk ratio of low CCr group for ≥ G3 ARs was 1.493 [95% CI: 0.710–3.145], although risk ratio of females was 2.486 [95% CI: 1.043–5.924]. Conclusions: Our study indicated that renal dysfunction may increase adverse reactions in the treatment of S-1 with concurrent RT for LAPC, and we should pay attention to renal function and consider for dose reduction.