HGCSG1902: Multicenter, prospective, observational study for patients with dysgeusia caused by chemotherapy for gastrointestinal cancer.

649 Background: Dysgeusia is the one of important adverse events in patients treated with chemotherapy because it could reduce daily oral intake and worsen patient’s nutritional status. It is said that the lack of zinc is often observed in patients with chemotherapy because taste buds cells injured by chemotherapy require large amounts of zinc for their regeneration and cytotoxic agents have the possibility of working as a chelator for zinc. Some retrospective studies showed that zinc administration may improve dysgeusia in patients treated with chemotherapy, however, there is no prospective study. Therefore, we planned this study to clarify the effect of zinc therapy on dysgeusia in patients with gastrointestinal cancer. Methods: This was a multicenter, prospective observational study. From February 2020 to June 2021, patients with dysgeusia during chemotherapy for gastrointestinal cancer were enrolled from 17 institutes in Japan. The investigator selected one of the following treatment: no intervention (N), polaprezinc administration (P: contains 34.1mg of zinc par daily normal dose), or zinc acetate hydrate administration (Z: contains 50-100mg of zinc par daily normal dose). Serum zinc levels were measured at baseline, after 6 and 12 weeks, respectively. Dysgeusia was assessed by questionnaires according to four criteria, CTCAE v5.0, Subjective Total Taste Acuity (STTA), Visual Analogue Scale (VAS), and Chemotherapy-induced Taste Alteration Scale (CiTAS) at the time of enrollment and after 12 weeks. Results: A total of 180 patients, 60 in each group, were enrolled in the study. The mean serum zinc levels in each group at baseline were similar (67.3, 66.6, and 67.5μg/dl in N, P, Z group, respectively) and lower than lower limit of normal. The mean alterations of serum zinc level from baseline to after 12 weeks were -3.8, +14.3, and +46.6μg/dl in N, P, Z group, respectively. The STTA score was significantly improved in the P group compared to the N group at 12 weeks (p = 0.045), whereas it was not improved in the Z group (p = 0.945). The association between the alteration values of serum zinc level and improvement of dysgeusia was not observed. Conclusions: In this study, administration of polarezinc or zinc acetate hydrate increased serum zinc levels, but there was no significant correlation between the degree of serum zinc elevation and the improvement of dysgeusia. The STTA score was improved only in P group, thus our results suggest there are any factors for improvement of dysgeusia by polaprezinc administration other than serum zinc levels. Clinical trial information: UMIN000039653.