Taste and Smell Alterations in Patients undergoing Hematopoietic Stem Cell Transplantations (HSCT)

Abstract

Background: Alterations in the chemosensory functions of taste and smell are common side effects experienced by patients undergoing standard oncology treatment. However, minimal data exists in patients undergoing hematopoietic stem cell transplantation (HSCT). Furthermore, most HSCT studies have focused solely on gustatory function and have been conducted only following completion of treatment. Aim: This study aimed to assess the magnitude and characteristics of gustatory and olfactory (chemosensory) function in patients receiving HSCT at the Seattle Cancer Care Alliance (SCCA) using objective and subjective chemosensory testing methods. We examined the relationship between chemosensory function and Quality of Life (QOL). Methods: In a prospective cohort study, patients aged 18+; scheduled to undergo HSCT at the SCCA were tested for gustatory and olfactory function at three time points: pre-transplant (baseline) and then on day 30 and day 80 post HSCT. Gustatory function was assessed following the procedures of the Rapid Screening test used by the Monell-Jefferson Taste and Smell Clinic, modified to use the general Labeled Magnitude Scale for response. Olfactory testing was conducted using the NIH Toolbox Odor Identification Test. Self-assessment of taste and smell function was performed using two different survey instruments: the Taste and Smell survey (Heald et al., 1998) and the EORTC QLQ-C30 & EORTC QLQ – H&N35. QOL was also assessed using the EORTC QLQ-C30 & EORTC QLQ – H&N35. Results: Twenty-nine patients were enrolled in the study between August 2014 and March 2015. A total of twenty-three patients were included in the analysis after exclusion of patients who were not tested at day 30 post-HSCT. Sixteen participants were tested at baseline, day 30 and day 80. The primary finding of this study is the decreased sensitivity (hypoguesia) for citric acid on day 30 and day 80 following HSCT; citric acid intensity was partially recovered by day 80. Increased sensitivity (hyperguesia) to a single concentration of sucrose at day 30 and a single concentration of NaCl at day 80 were also observed. Olfactory identification scores were unchanged from baseline to day 30. Results of the QOL data analysis indicated that most patients quality of life was reduced at 30 days post-transplant, however, quality of life was restored to an acceptable level of functioning and symptoms by 80 days after HSCT. Notably, some areas remain impaired, such as social functioning and dry mouth. Conclusion: Patient reports of altered taste function were collaborated by objective testing. Taste was not reduced across the board, however. Rather specific declines in sour (citric acid) perception were noted. Selective hypersensitivity was seen for some taste solutions. No obvious issues were found with olfactory function in relation to HSCT. It would be helpful if future investigations confirm our results with a larger number of patients. That would aid in developing food products and/or nutritional supplements that appeal to patients experiencing altered taste functions post HSCT.