PurposeTo test the hypothesis that daily intravenous pre-hydration decreases renal toxicity and improves chemotherapy adherence in patients receiving daily cisplatin to concurrent radiotherapy for locally advanced non-small cell lung cancer (NSCLC). Patients and methodsPatients with locally advanced NSCLC were treated between 2008 and August 2012 with daily 6mg/m2 cisplatin as a bolus injection in 10ml; of saline and 66Gy/24fr radiotherapy in 32days. Since January 2011, the administration of cisplatin was routinely preceded by intravenous pre-hydration with 1L of natriumchloride 0.9%. Patients were divided in a pre-hydrated (PH) and non-pre-hydrated (NPH) cohort. Serum-creatinine and glomerular filtration rate (GFR) were assessed twice weekly during treatment. Retrospectively, baseline data, toxicity, treatment adherence and efficacy data were compared. ResultsOf the 356 patients 232 NPH patients and 100 PH patients were eligible. Patient-and treatment characteristics compared equally. The median of the maximum decrease in GFR was 24% and 8% for NPH and PH (p<0.01), respectively. Sixty-nine percent of the patients in the NPH group completed the 24 administrations of cisplatin, as compared to 83% of the PH group (p<0.01). Nineteen percent vs. 2% of the patients in the NPH and PH group discontinued cisplatin treatment because of renal toxicity. Surprisingly, the incidence of acute esophageal toxicity grade ⩾2 decreased following prehydration: 62% vs. 34% (p<0.001) for the NPH and PH groups, respectively. The one-year survival was comparable between groups (75% for NPH and 71% for PH). ConclusionDaily pre-hydration was associated with a reduced rate of both renal and acute esophageal toxicity and an increased chemotherapy adherence in patients receiving daily dose of cisplatin and concurrent radiotherapy for locally advanced NSCLC.