Changes in taste and smell function during adjuvant chemotherapy in patients with colon cancer: a prospective cohort study

Background & aims: Adjuvant chemotherapy for high-risk stage II or stage III colon cancer improves survival, but frequently induces side effects, including changes in taste (hypogeusia) and smell (hyposmia) function. These alterations in taste and smell function may reduce appetite and nutritional intake, increasing the risk of malnutrition and compromising treatment tolerance and quality of life. Objective data on these changes during chemotherapy are limited. The aim of this study was to investigate changes in taste and smell function during adjuvant chemotherapy in patients with colon cancer. Methods: In this relatively small prospective cohort study, eleven patients with high-risk stage II or III colon cancer receiving capecitabine or CAPOX were included. Taste and smell function were assessed using Taste Strips and Sniffin’ Sticks before, during, and after chemotherapy. Paired-samples t-tests compared taste and smell function at each time point to baseline. Results: Significant declines in taste (T1; mean difference = -1.33, p = 0.022) and smell (T1; mean difference = -5.11, p = 0.017) were observed after the first chemotherapy cycle. Baseline hypogeusia and hyposmia were present in 33% and 44% of patients, respectively. During treatment, hypogeusia ranged from 33–44% and hyposmia from 44–78%, with marked inter- and intra-individual variability. While most patients maintained normogeusia, hyposmia was more common at multiple time points. Conclusion: Adjuvant chemotherapy is associated with clinically relevant, but heterogeneous changes in taste and smell, particularly during the initial phase of chemotherapy. These alterations may impair nutritional intake, highlighting the need for early, individualized dietary interventions. Combining objective and patient-reported assessments may optimize supportive care, enhancing treatment tolerance and quality of life. Despite the small sample size, which substantially limits generalizability, the in-depth analysis highlights significant variability in taste and smell function both between patients and across chemotherapy cycles, highlighting that chemosensory changes are neither uniform nor static.