Caries-associated oral microbiome in head and neck cancer radiation patients: a longitudinal study

Abstract

Head and neck cancer (HNC) therapy often leads to caries development. Our goal was to characterize the oral microbiome of HNC patients who underwent radiation therapy (RT) at baseline (T0), and 6 (T6) and 18 (T18) months post-RT, and to determine if there was a relationship with increased caries. HOMINGS was used to determine the relative abundance (RA) of >600 bacterial species in oral samples of 31 HNC patients. The DMFS score was used to define patient groups with tooth decay increase (DMFS[+]) or no increase (DMFS[-]).A change in microbiome beta-diversity was observed at T6 and T18. The Streptococcus mutans RA increased at T6 in both DMFS[+] and DMFS[-] groups. The RA of Prevotella melaninogenica, the species often associated with caries in young children, decreased at T6 in the DMFS[-] group. The RA of the healthassociated species, Abiotrophia defective, decreased in the DMFS[+] group. The oral microbiome underwent significant changes in radiation-treated HNC patients, whether they developed caries or not. Caries rates were not associated with a difference in salivary flow reduction between DMFS [+] andDMFS[-] groups. Patients who develop caries might be more susceptible to certain species associated with oral disease or have fewer potentially protective oral species.

The Role of the Microbiome in Oral Squamous Cell Carcinoma with Insight into the Microbiome–Treatment Axis

“…The oral microbiome has been shown to undergo significant changes during and after radiotherapy for OSCC [190]; however, the use of intensely modulated radiotherapy can help protect and stabilise the oral microbiome compared to conventional forms of radiation [191]. The side effects of radiation for OSCC include the development of mucositis, xerostomia, taste modification, dysphagia, osteoradionecrosis and trismus [192].…”

“…Soil genera such as Derxia and Luteococcus, the latter isolated from blood, have also been sequenced from patients with HNC undergoing radiation [199]. Interestingly, a significant decrease in abundance occurred post-radiation therapy for the OSCC-associated species Prevotella melaninogenica in those with HNC [190]. With relation to osteoradionecrosis, the most predominant species from affected mandibles were Campylobacter gracilis, Fusobacterium nucleatum, Streptococcus intermedius, Peptostreptococcus, and Prevotella species [200].…”

Dental caries following radiotherapy for head and neck cancer: A systematic review

“…Again, this figure should be interpreted with caution given the high heterogeneity determined (p<0.001, I 2 88.6%). Excluding the randomised controlled trial conducted by Spak et al [24] due to a perceived high risk of bias, as well as observational studies by Rocha et al, [56] Duarte et al [64], Frydrych et al, [65] Jham et al, [67] Sun et al, [75] Meng et al, [69] Siala et al, [74] and Mougeot et al [70] on the basis of lower Newcastle-Ottawa Scale scores, [78] a pooled estimate of 0.30 (95% CI 0.19,0.44) was calculated for the proportion of patients who developed dental caries post-radiotherapy. Heterogeneity, however, was only marginally reduced after the exclusion of these studies (p<0.001, I 2 87.2%).…”

Acute Radiation Syndrome and the Microbiome: Impact and Review

“…The oral cavity has a delicate microbiota balance that can be directly affected not only by irradiation but also from changes in saliva composition and/or volume due to radiation-induced damage of the salivary glands, which are particularly radio-sensitive organs ( Kałużny et al, 2014 ). Since the 1970s, radiation-induced xerostomia has been known to affect the oral microbiota ( Brown et al, 1975 ; Brown et al, 1978 ; Sroussi et al, 2017 ; Mougeot et al, 2019 ; Breslin and Taylor, 2020 ), and it has been recently discovered that Candida infections in patients who received radiotherapy are often from species that are more virulent and drug-resistant ( Tarapan et al, 2019 ). This is particularly concerning, given that Candida is the fourth most common cause of bloodstream infections among hospital patients in the United States and can be fatal ( Hajjeh et al, 2004 ; Lone and Ahmad, 2019 ).…”