Smell and Taste Impairments in Head and Neck Cancer Patients—A Scoping Review

Head and neck cancer affects millions worldwide. The risk factors are numerous, including smoking, alcohol consumption, and human papillomavirus to name a few. While improved preventative, diagnostic, and treatment methods have decreased mortality rates, the treatments (chemotherapy, radiotherapy, or surgery) often result in smell and/or taste impairments. These can impact quality of life during and after cancer treatment. A scoping review was performed to understand current research and future directions regarding smell and taste impairments in head and neck cancer patients. PRISMA guidelines were followed and Rayyan.ai was used to search and compile journal articles. Three databases, EBSCOhost, Google Scholar, and PubMed, were also searched. Search terms included smell, taste, dysgeusia, ageusia, hypogeusia, parosmia, anosmia, hyposmia, dysosmia, and head and neck cancer. A total of 1580 articles were found through Rayyan.ai and 8022 were found through the three databases, which were manually screened. Articles assessing patients with a different malignancy, benign tumors, pediatric populations, animal studies, abstracts, and review articles were excluded. A total of 47 articles were found using this strategy. Of those we identified, 37 articles discussed taste impairments, 12 articles discussed smell impairments, and 3 articles discussed treatments for smell and/or taste impairments. All 37 articles concluded that there was some taste alteration in head and neck cancer patients due to their treatment. However, the specific taste qualities (sweet, sour, salty, or bitter) that were impaired, whether taste function returned to baseline, and which treatments led to impairments varied. For the 12 studies that assessed smell impairments, the results also varied. Some studies found significant objective impairments in smell while others found no significant impairment. Zinc sulfate was not found to be an effective treatment option for taste impairments; however, a liposomal spray showed some potential. Future studies should aim to understand which treatments and types of head and neck cancer lead to chemosensory impairments, whether chemosensory alterations negatively impact a patient's nutritional status, and treatments or preventative measures for smell and taste changes.