Radiation Therapy–Induced Changes of the Nasopharyngeal Commensal Microbiome in Nasopharyngeal Carcinoma Patients

Purpose: The human commensal microbiome has been suggested to be involved in the regulation of response to anticancer therapies. However, little is known regarding changes in commensal microbes in patients with cancer during radiation therapy. We conducted a prospective, longitudinal proof-of-concept cohort study with patients with newly diagnosed nasopharyngeal carcinoma (NPC) who underwent radiation therapy-based treatment. Methods and Materials: Nasopharyngeal swabs were collected before radiation therapy, twice per week during radiation therapy, and after radiation therapy. The nasopharyngeal microbiome was assessed using 16S rRNA amplicon sequencing. A patient's response to treatment was measured 3 months after the completion of radiation therapy as a short-term clinical outcome. In total, 39 NPC patients with 445 nasopharyngeal samples were analyzed. Results: There was stable temporal change in the community structure of the nasopharyngeal microbiome among patients with NPC during treatment (P =.0005). Among 73 abundant amplicon sequence variants (ASVs), 7 ASVs assigned to genus Corynebacterium decreased significantly during the treatment (W-statistic >80%); 23 ASVs showed statistically significant changes in the ratio of abundance between early and late responders during treatment (false discovery rate <0.05). Conclusions: This study addressed stable temporal change in the nasopharyngeal microbiome among patients with NPC during radiation therapy–based treatment and provided preliminary evidence of an association with a short-term clinical outcome.