Prevalence and Temporal Course of Chemotherapy-Induced Ageusia and Anosmia in Breast, Colorectal, and Lung Cancer Patients: A Prospective O0bservational Study

Abstract

Background: Taste and smell disturbances are common but under-recognized consequences of cancer 
chemotherapy. This study describes the prevalence and 12-week temporal course of chemotherapy-induced 
ageusia and anosmia across four regimens used for breast, colorectal, and lung cancer.
Methods: In this prospective observational study conducted in the Department of Medical Oncology, 
King George Hospital, Visakhapatnam, India, 100 adults undergoing chemotherapy (trastuzumab or 
adriamycin for breast cancer; capecitabine for colorectal cancer; paclitaxel for lung cancer) were enrolled 
and followed for 12 weeks. Taste and smell symptoms were assessed with the Chemotherapy-Induced 
Taste Alteration Scale (CiTAS) and the Self-Administered Odor Questionnaire (SAOQ) at intervals coinciding 
with chemotherapy cycles.
Results: Ageusia and anosmia were each reported by all 100 patients (100%; 95% exact CI 96.4–100%). 
The cohort was 51% male and 49% female; sex was completely or almost completely confounded with 
regimen (both breast-cancer regimens were 100% female, the lung-cancer regimen 100% male, and 
the colorectal-cancer regimen 81% male). Female patients were significantly older than male patients 
(53.6±13.9 vs 46.2±12.2 years, p=0.005). Across all four regimens, most patients’ symptoms were first 
documented within weeks 1–5 of treatment (59.1–65.5% for ageusia, 54.6–68.2% for anosmia), with 
progressively fewer patients documented in later windows — except for capecitabine, for which the 
proportion recorded at weeks 11–15 (22.2%) exceeded that at weeks 6–10 (18.5%). Planned analyses of 
CiTAS/SAOQ severity scores and EORTC QLQ-C30 quality-of-life domains could not be verified against the 
scoring procedures specified for these instruments and are not reported (see Limitations).
Conclusion: In this single-center cohort, chemotherapy-induced ageusia and anosmia were universal, 
and their timing differed somewhat by regimen, with a possible late-phase increase in anosmia under 
capecitabine that warrants confirmation. Because sex, cancer type, and regimen were almost entirely 
confounded and several planned quality-of-life analyses could not be validated, these findings should be 
treated as descriptive and hypothesis-generating. Larger, multi-center studies with independently verified 
instrument scoring are needed