The relationship between treatment time of gemcitabine and development of hematologic toxicity in cancer patients.

Although gemcitabine is frequently used in the treatment of cancer, it is associated with myelosuppression. An animal study showed that the tolerability of gemcitabine varied with changes in treatment time; however, no clinical data have verified this finding. The purpose of this study was to determine the relationship between treatment time and development of hematologic toxicity in patients treated with gemcitabine. Gemcitabine-induced hematologic toxicity was retrospectively investigated in 77 patients. Patients were divided into two treatment-time groups: 9:00 and 15:00. Hematologic toxicity was evaluated on day 8 and 15 after treatment. On day 8 and 15, the changing count of white blood cells was significantly reduced in patients treated at 15:00 compared with those treated at 9:00 (p<0.01 and p<0.05, respectively). On days 8 and 15, the changing count of platelet was significantly reduced in patients treated at 15:00 compared with those treated at 9:00 (p<0.05). The incident of over common terminology criteria for adverse events (CTCAE) grade 2 white blood cell decreased was significantly reduced in patients treated at 15:00 compared with those treated at 9:00 (p=0.048, odds ratio=2.92). In conclusion, this cohort study demonstrated that gemcitabine-induced hematologic toxicity could be alleviated by treating patients at 9:00.