Head and neck (NH) cancers can develop in several distinct locations including the nasal cavity, sinuses, lips, mouth, salivary glands, throat, or larynx. A known side effect of head and neck (HN) cancer is that patients lose their sense of smell after receiving radiotherapy. However, scientists don’t fully understand the potential mechanistic links between radiotherapy and smell dysfunction.
To evaluate whether radiotherapy directly affects smell, a team of researchers conducted a clinical trial involving HN cancer patients who received curative radiotherapy. The research team recently published the results of their trial in JAMA Network Open.
The study focused on patients receiving intensity-modulated RT (IMRT), a specialized type of radiotherapy that uses computers to augment the shape, intensity, and direction of radiation beams targeting tumor cells. This technique allows greater radiation to focus on tumors while sparing nearby healthy tissues. Patients receiving IMRT often experience few side effects of their treatment due to the precision allowed by this advanced technique.
The study enrolled 63 patients receiving IMRT who underwent multiple assessments of olfactory function prior to treatment and at several time points after treatment. The researchers then compared the data collected from these assessments with the radiation dose received in the olfactory region. Patients with NH cancers affect various areas, including the oral cavity and the nasopharynx.
The analysis showed a positive correlation between radiation dose and olfactory dysfunction, with impairment increasing in a dose-dependent manner. Researchers identified 22 Gy as the threshold beyond which olfactory impairment became likely. Receiving more than 22 Gy was the only risk factor for olfactory dysfunction found in the study.
This study is the first to demonstrate a correlation between radiotherapy and olfactory dysfunction in HN cancer patients. The finding that doses above 22 Gy increase smell-related side effects offers important guidance for treatment planning.
Sources: Cancer Imaging, JAMA Netw Open
