Neutrophils, also known as polymorphonuclear leukocytes (PMNs), form a significant component of the innate host response, and the consequence of the interaction between the oral microbiota and PMNs is a crucial determinant of oral health status. The impact of radiation therapy (RT) for head and neck tumour (HNT) treatment on the oral innate immune system, neutrophils in particular, and the oral microbiome has not been thoroughly investigated. Therefore, the objective of this study was to characterize RT-mediated changes in oral neutrophils (oPMNs) and the oral microbiome in patients undergoing RT to treat HNTs. Oral rinse samples were collected prior to, during and post-RT from HNT patients receiving RT at Dental Oncology at Princess Margaret Cancer Centre. The oPMNs counts and activation states were analysed using flow cytometry, and the oral microbiome was analysed using 16S rRNA gene sequencing. Statistically significant (p < 0.05) drops in oPMN counts and the activation states of the CD11b, CD16, CD18, CD64 and H3Cit markers from pre-RT to post-RT were observed. Moreover, exposure to RT caused a significant reduction in the relative abundance of commensal Gram-negative bacteria and increased the commensal Gram-positive microbes. Ionizing radiation for the treatment of HNTs simultaneously decreased the recruitment of oPMNs into the oral cavity and suppressed their activation state. The oral microbiome composition post-RT was altered significantly due to RT which may favour the colonization of specific microbial communities unfavourable for the long-term development of a balanced oral microbiome.

Purpose: The management of head and neck cancer (HNC) patients requires balancing disease control with structural, cosmetic, and functional deficits that can negatively impact quality of life (QoL). Therefore, understanding the physical, emotional and social aspects of QoL of patients throughout their HNC treatment process can help providers better treat this populations of patients in order to improve their QoL. Methods: This was a prospective cohort study of sixty-eight consecutive patients with HNC receiving curative intent RT at Princess Margaret Cancer Centre who had completed the self-administered UW-QoL v4 pre-RT, Mid-RT, 1-month and 6-months post-RT. Results: All scores on the questionnaire decreased mid-RT, with taste and saliva demonstrating the greatest decrease (p <. 05). All scores increased and therefore improved 1-month post-RT and further improved at 6-months post-RT (p <.05). Mean scores did not return to the mean pre-RT levels for the domains swallowing, taste, saliva, and for the physical function composite scores. Conclusions:HNC patients undergoing RT treatment need to be supported and monitored by health care providers for alterations in QoL during and post-RT, especially with respect to their taste and saliva.