The Persistence of Streptococcus mutans in Nasopharyngeal Carcinoma Patients after Radiotherapy

Interconnected influences of tumour and host microbiota on treatment response and side effects in nasopharyngeal cancer

This study elucidates the intricate relationship between nasopharyngeal carcinoma (NPC), a significant malignancy predominant in Asia with notable global incidence and mortality rates, and the host microbiota, including those of tumour, nasal, nasopharyngeal, oral, oropharyngeal, and gut communities. It underscores how the composition and diversity of microbiota are altered in NPC, delving into their implications for disease pathogenesis, treatment response, and the side effects of therapies. A consistent reduction in alpha diversity across oral, nasal, and gut microbiomes in NPC patients compared to healthy individuals signals a distinct microbial signature indicative of the diseased state. The study also shows unique microbial changes tied to different NPC stages, indicating a dynamic interplay between disease progression and microbiota composition. Patients with specific microbial profiles exhibit varied responses to chemotherapy and immunotherapy, underscoring the potential for treatment personalisation based on microbiota analysis. Furthermore, the side effects of NPC treatments, such as oral mucositis, are intensified by shifts in microbial communities, suggesting a direct link between microbiota composition and treatment tolerance. This nexus offers opportunities for interventions aimed at modulating the microbiota to alleviate side effects, improve quality of life, and potentially enhance treatment efficacy. Highlighting the dual potential of microbiota as both a therapeutic target and a biomarker for NPC, this review emphasises its significance in influencing treatment outcomes and side effects, heralding a new era in NPC management through personalised treatment strategies and innovative approaches.

Radiation-associated changes in saliva composition of head and neck cancer patients: A systematic review

Xerostomia is a common radiation-associated toxicity in patients with head and neck cancer. Although several studies examined the decrease in saliva production due to radiotherapy (RT) and investigated the factors associated with this side effect, little is known about the change in radiation-associated saliva composition. This systematic review is the first to summarize existing data and give an overview of the change in pH/buffer capacity, electrolytes, proteins, enzymes, and mucins due to radiation to the salivary glands. Literature search was performed in PubMed and Embase with 47 articles finally eligible for the review, analyzing the saliva composition at several time points before, during and/or after RT, or comparing findings in irradiated patients to a healthy control group. Overall, RT leads to a substantial decrease in salivary pH and buffer capacity. For sodium, chloride and calcium ion, as well as amylase, an increased concentration or activity during RT was reported in most of the studies, followed by a subsequent decrease either already during RT or after the end of treatment. Different trends have been described for the total protein concentration during and after RT. Lactoferrin, however, increased considerably, especially in the first phase of RT. Mucin 5B (MUC5B) concentrations showed a slight increase during RT and concentrations around baseline values again six months post-radiotherapy.

Assessment of hyperbaric oxygenation treatment response in parotid glands by T 2 mapping following radiotherapy for head and neck tumours

Background

The study was designed to evaluate the influence of hyperbaric oxygenation therapy (HBOT) on the parotid gland in patients following radiotherapy for head and neck tumours.

Patients and methods

HBOT response was monitored by 3T magnetic resonance imaging (MRI) using T₂ mapping and subsequent measurement of mean T₂ and T₂ variability as well as by salivary tests (salivary flow, buffer capacity, and pH). Eighteen patients previously treated with irradiation doses between 50 and 80 Gy as well as 18 healthy gender and age matched controls were enrolled. MRI was performed prior to HBOT (40.2 ± 20 months after radiotherapy) and after 20 daily HBOT at 2.5 ATA (absolute atmosphere). Each HBOT consisted of breathing 100% oxygen for 90 minutes.

Results

Significant differences in mean T₂ prior to HBOT were observed between the ipsilateral irradiated (121 ± 20 ms), contralateral parotids (107 ± 21) and control group (96 ± 12 ms). A positive correlation in patients between T₂ variability and irradiation dose was detected in contralateral parotids before HBOT (R = 0.489, p = 0.0287). In addition, negative correlations were observed between mean T₂ in the ipsilateral as well as the contralateral gland and salivary flow before and after HBOT. Negative correlations between mean T₂, T₂ variability and pH of unstimulated saliva were also observed in the sides of parotid before and after HBOT.

Conclusions

The study confirmed that T₂ mapping had a potential for monitoring the differences between irradiated and normal parotid glands. It could also be useful in the assessment of the glandular tissue response to HBOT.

Pretreatment Systemic Immune-Inflammation Index Predict Needs for Teeth Extractions for Locally Advanced Head and Neck Cancer Patients Undergoing Concurrent Chemoradiotherapy

Background

To evaluate the utility of pretreatment systemic immune-inflammation index (SII) in predicting the teeth caries and need for tooth extraction after concurrent chemoradiotherapy (C-CRT) for locally advanced squamous-cell head and neck cancer (LA-SCHNC) patients.

Methods

The records of LA-SCHNC patients who underwent formal dental evaluations at pre- and post-C-CRT periods were retrospectively analyzed. The pretreatment SII values were calculated using the platelet, neutrophil, and lymphocyte measures acquired on the first day of C-CRT: SII=Platelets×neutrophils/lymphocytes. Receiver operating characteristic (ROC) curve analysis was employed to identify the ideal pre-C-CRT SII cutoff that may predict the teeth caries and the need for tooth extraction after the C-CRT. The primary endpoint was the link between the pre-C-CRT SII and the need for tooth extraction during the follow-up period.

Results

A sum of 126 patients were included. Median follow-up was 4.9 years (range: 2.7–7.8). Nasopharyngeal and laryngeal cancers comprised the majority (75.4%) study cohort. Post-treatment teeth extractions were reported in 62.7% patients. The optimal cutoff was 558 [Area under the curve (AUC): %76.8 sensitivity: 72.3%; and specificity: 70.9%] that grouped the patients into two subgroups with significantly different post-C-CRT tooth extraction rates: Group 1: SII≤558 (n = 70) and SII>558 (n = 56), respectively. Correlation analysis revealed a significant relationship between the pretreatment SII and the tooth extraction rates after the C-CRT (r_s:0.89: P = 0.001). The comparative analysis displayed that the teeth extractions rates were significantly higher in the SII>558 group (77.1% versus 51.4% for SII≤558; Hazard ratio: 1.68; P = 0.001). Further analyses showed that the pre-C-CRT SII>558 was the unique factor associated with meaningfully higher necessities for post-C-CRT teeth extractions.

Conclusion

The present outcomes intimated that high pretreatment SII levels were linked to significantly increased post-treatment teeth extractions in LA-SCHNC patients undergoing definitive C-CRT.

Late radiation effects in survivors of head and neck cancer: State of the science

Head and neck squamous cell carcinoma is one of the most common neoplasms. Radiotherapy (RT) plays an essential role in the management of such cases. Despite advances in the technique, hyposalivation, xerostomia, dysphagia, trismus, radiation caries, and osteoradionecrosis remain significant late complications of RT. The aim of this narrative review was to summarize and update the main findings related to late side effects of radiotherapy in survivors of head and neck cancer (HNC). Such effects limit the ability to speak, ingest food and medications, and breathe and also exert a negative impact on social well-being and quality of life. This review highlights research in the field for both researchers and clinicians, assisting in the prevention and management of these adverse conditions. The findings can contribute to improving preventive management and multidisciplinary interventions for HNC patients.

Evaluation of Alteration in Oral Microbial Flora Pre- and Postradiation Therapy in Patients with Head and Neck Cancer

Introduction:

For decades now, head and neck cancer (HNC) remains to be one of the deadliest; per se the treatment for the same has been evolving for the past years. Radiation therapy (RT) has been one among the various treatment modalities adopted to treat HNC. The fact that RT can affect the quality of life in these patients cannot be denied. In patients with HNC, these can bring about a wide array of lesions in oral cavity and its associated structures as these areas are invariably affected due to exposure to radiation as such. These include alteration in salivary parameters, changes in microbial flora, and occurrence of radiation caries.

Aim:

In our study we aimed at assessing the alteration in oral microbial flora inclusive of Streptococcus mutans and Lactobacillus colony count before and after RT.

Materials and Methods:

Saliva and plaque samples were collected from patients with HNC, who were prescribed to undergo intensity-modulated radiation therapy (IMRT) amounting to a mean radiation dosage of 60 Gy units. The aforementioned samples were collected at three different intervals, before, immediately after, and 6 months after RT. The samples were cultured in selective media in three different dilutions (1:10, 1:100, and 1:1000). Following with colony counting is carried out using a standardized colony counter.

Conclusion:

The results showed a significant alteration in microbial flora pre- and post-RT. Individual parameters do not show a single stand in causing these changes. Moreover, these changes seem to have earned a multifactorial contribution.

Hyperbaric oxygen treatment for the management of radiation-induced xerostomia

INTRODUCTION

Hyperbaric oxygen therapy (HBOT) is widely used for the treatment of the late effects of radiation therapy. We report a prospective observational cohort study of 51 patients designed to examine the effectiveness of hyperbaric oxygen treatment (HBOT) for xerostomia following radiotherapy.

METHODS

Objective (saliva volume) and subjective (quality of life scoring and visual analogue scale (VAS) of discomfort) measurements associated with xerostomia were compared prior to commencement of HBOT, after 30 sessions (over 6 weeks) of HBOT at 243 kPa for 90 minutes daily for five days per week and at 6-week review (12 weeks from commencement).

RESULTS

One hundred and one courses of treatment in 99 patients were examined. For 53 (53%) courses in 51 patients, data were recorded before and after HBOT and so could be included in the analysis. Thirty-four (34%) of these patients had complete data for all three time points. The unit of study was per treatment course, not per person. There were no major complications to HBOT. There was a statistically significant difference in saliva volume following HBOT (P = 0.016). The mean saliva volume increase was 0.9 mL over a 5-min collection period (95% CI 0.2-1.5). There was also a statistically significant improvement in discomfort after HBOT (P < 0.001) and QOL (P < 0.001). The mean visual analogue scale for discomfort (VAS on a 0-10 scale) score decreased by 1.4 units (95% CI 0.7-2.1), whilst the mean QOL score was 10 points lower after treatment (95% CI 5.9-14.4).

CONCLUSION

Hyperbaric oxygen therapy may be a safe and effective treatment for symptoms of xerostomia after radiation therapy and should be considered when available.

Mucosal microflora in head and neck cancer patients

OBJECTIVE

To analyse the tongue and buccal microflora prospectively in head and neck cancer patients treated with radiation therapy (RT).

METHODS

In 33 dentate patients, microbial samples from the tongue and buccal mucosa were collected pretreatment, during treatment, and 6 months, 1 year and 2 years post-treatment. Microorganisms associated with oral health and oral disorders were analysed using cultivation technique. Oral mucositis was scored at the appointment during treatment.

RESULTS

Compared with pretreatment, lactobacilli and Candida increased on the tongue, while streptococci and Neisseria decreased during treatment. Two years post-treatment, Neisseria and Prevotella were decreased and Candida increased. On the buccal mucosa, an increased growth of lactobacilli and increased detection frequencies of the opportunistic bacteria Staphylococcus aureus, Gram-negative enteric rods and enterococci were seen during treatment compared with pretreatment. Seventy per cent showed severe mucositis during treatment. Two years post-treatment the total count as well as streptococci, Neisseria and Fusobacterium nucleatum were decreased and lactobacilli increased compared with pretreatment.

CONCLUSION

Despite improvements in treatment for cancer in the head and neck region, microorganisms associated with oral health decrease during treatment and mucosal pathogens increase. Two years post-treatment, levels of acid-tolerant (lactobacilli and Candida) were increased, while acid-sensitive microorganisms (Neisseria and F. nucleatum) were decreased, plausibly due to persisting decreased salivary secretion rate.

Supragingival and subgingival microbiota from patients with poor oral hygiene submitted to radiotherapy for head and neck cancer treatment

OBJECTIVE

This case-control study aimed to evaluate the effects of conventional radiotherapy (RT) on the prevalence and populations of oral microorganisms in head and neck cancer patients who did not receive adequate preventive dental care. It was hypothesized that side effects of radiotherapy could be associated with radiation dose, microbiological aspects, and socioeconomic conditions of the patients.

DESIGN

Twenty-eight dentate patients with head and neck cancer submitted to RT were included in the study. Radiation dose received varied from 4320 to 7020 cGy. Patients with the same demographic and health conditions, but no history of cancer or antineoplastic treatment were used as controls. Clinical examinations were carried out before RT, 15-22 days after starting RT, immediately after and 6 months after RT. Supra and subgingival biofilms were collected and cultivated onto selective and non-selective media. Isolates were identified by biochemical and physiological characteristics. Stimulated and unstimulated salivary flow rate and saliva buffer capacity were also determined.

RESULTS

Mucositis, dermatitis, xerostomia, dysgeusia, dysphagia and candidiasis were common after starting RT and during the treatment period. Xerostomia was followed by a decrease in salivary pH and buffer capacity, which showed association with the increase of cariogenic cocci and yeast populations, which were also associated with deterioration of hygiene. Candida and family Enterobacteriaceae showed increased prevalence with RT, and were associated with the occurrence of mucositis and xerostomia.

CONCLUSIONS

Modifications in oral biofilms of irradiated patients showed association with xerostomia and hygiene conditions, which reinforces the necessity of improving patient compliance to oral health care programs.

Natural Immunoreactivity of Secretory IgA to Indigenous Strains of Streptococcus mutans From Chinese Spousal Pairs

Background

Dental caries is a well-known biofilm-mediated disease initiated by Streptococcus mutans, which should infect and colonize in a milieu perfused with components of the mucosal immune system. Little is known, however, regarding the relationship between the natural secretory IgA activity and S. mutans of a variety of diverse genotypes.

Objectives

The current study aimed to use spousal pairs to investigate the natural immunoreactivity of salivary secretory IgA to different genotype strains of S. mutans.

Patients and Methods

Indigenous strains were characterized from nine spousal pairs using polymerase reaction chain (PCR) and arbitrarily primed polymerase chain reaction (AP-PCR) by genotype monitoring. Unstimulated submandibular/sublingual secretions were collected and the concentrations of secretory IgA were determined by the enzyme-linked immunosorbent assay (ELISA). Each saliva sample was examined by Western blot to analyze the immunoreactivity of naturally occurring salivary secretory IgA antibodies for his/her own indigenous strain, spouse’s strain and reference strains including S. mutans GS-5 and Ingbritt (C).

Results

The results showed that naturally induced salivary IgA antibodies against S. mutans were present in all subjects. Almost all subjects had the similar individual immunoblotting profiles to different genotype strains.

Conclusions

The current study indicated that the immunoreactivity of secretory IgA might have no direct correlation with the colonization of indigenous flora and rejection of exogenous strains in adults. The relationship of microbes, host and dental caries should be in the light of coevolved microecosystem as a whole, but not caused by one factor alone.

Radiation caries in nasopharyngeal carcinoma patients after intensity-modulated radiation therapy: A cross-sectional study

Background/purpose

The exact dose of intensity-modulated radiation therapy (IMRT) associated with tooth damage is mostly unknown. We aim to evaluate the severity of dental lesions after IMRT and the correlation with the radiation dose to the dentition in patients with nasopharyngeal carcinoma (NPC).

Materials and methods

This was a cross-sectional study of 42 patients with NPC who completed IMRT in 2011. Each premolar tooth was divided into 13 sites. Teeth were evaluated using a validated index and subsequently categorized at each divided site. The relationship between dose distribution and the caries severity score was analyzed using logistic models. The odds of developing caries damage were evaluated using odds ratios.

Results

A total of 4342 sites from 334 premolar teeth were evaluated. For sites exposed to 30–60 Gy, the odds of developing caries damage were 12–200 times greater compared with sites unexposed to IMRT. A new radiation caries lesion was likely to occur when the dose was >35.8 Gy after 17 days' radiation therapy (P < 0.05).

Conclusion

The findings suggest that new tooth damage was likely to occur at doses > 35.8 Gy, and care should be taken throughout the treatment planning process to limit tooth doses to < 50 Gy in NPC patients.

Investigation of salivary function and oral microbiota of radiation caries-free people with nasopharyngeal carcinoma

Radiation caries have been reported to be correlated with radiotherapy-induced destruction of salivary function and changes in oral microbiota. There have been no published reports detailing patients who have remained radiation caries-free following radiotherapy for nasopharyngeal carcinoma. The aim of this study was to investigate the relationship between salivary function, oral microbiota and the absence of radiation caries. Twelve radiation caries-free patients and nine patients exhibiting radiation caries following irradiated nasopharyngeal carcinoma were selected. V40, the dose at which the volume of the contralateral parotid gland receives more than 40 Gy, was recorded. Stimulated saliva flow rate, pH values and buffering capacity were examined to assess salivary function. Stimulated saliva was used for molecular profiling by Denaturing Gradient Gel Electrophoresis. Mutans streptococci and Lactobacilli in saliva were also cultivated. There were no significant differences in V40 between radiation caries-free individuals and those with radiation caries. Compared with normal values, the radiation caries-free group had significantly decreased simulated saliva flow rate, while there were no significant differences in the saliva pH value and buffering capacity. Similar results were observed in the radiation caries group. There was no statistical difference in microbial diversity, composition and log CFU counts in cultivation from the radiation caries-free group and the radiation caries group. Eleven genera were detected in these two groups, among which Streptococcus spp. and Neisseria spp. had the highest distribution. Our results suggest that changes in salivary function and in salivary microbiota do not explain the absence of radiation caries in radiation caries-free individuals.

Changes of saliva microbiota in nasopharyngeal carcinoma patients under chemoradiation therapy

OBJECTIVE

A growing body of evidence has implicated human oral microbiota in the aetiology of oral and systemic diseases. Nasopharyngeal carcinoma (NPC), an epithelial-originated malignancy, has a complex aetiology not yet fully understood. Chemoradiation therapy of NPC can affect oral microbiota and is usually accompanied by plaque accumulation. Thus, the study aimed to understand the diversity, divergence and development of the oral microbiota in NPC patients and their associated treatment, which might provide useful insights into disease aetiology and treatment side effects.

DESIGN

A longitudinal study was designed that included three Chinese adults with NPC. Saliva samples were collected at three time points: prior to the chemoradiation treatment (carcinoma baseline, or CB), 7 months post-treatment (carcinoma-after-therapy phase 1 or CA1) and 12 months post-treatment (carcinoma-after-therapy phase 2 or CA2). Pyrosequencing of the bacterial 16S ribosomal DNA (rDNA) V1-V3 hypervariable region was employed to characterise the microbiota. Saliva samples of three healthy subjects from our former study were employed as healthy controls. Principal coordinates analysis (PCoA), Metastats and random forest prediction models were used to reveal the key microbial members associated with NPC and its treatment programme.

RESULTS

(1) In total, 412 bacterial species from at least 107 genera and 13 phyla were found in the saliva samples of the NPC patients. (2) PCoA revealed that not only were the microbiota from NPC patients distinct from those of healthy controls (p<0.001) but also that separation was found on the saliva microbiota between pre- and post-therapy (p<0.001) in the NPC samples. (3) At the genus level and the operational taxonomic unit (OTU) level, Streptococcus was found with lower abundance in NPC samples. (4) Chemoradiation therapy did not incur similar changes in microbiota structure among the three NPC patients; the microbiota in one of them stayed largely steady, while those in the other two showed significant alteration.

CONCLUSIONS

This is the first study employing culture-independent techniques to interrogate the phylogenetic diversity, divergence and temporal development of oral microbiota in NPC patients. Our results indicated that certain bacterial taxa might be associated with NPC and that oral microbiota of NPC patients might respond to the chemoradiation therapy in a host-specific manner. Further investigation with larger sample size should help to validate the links between oral microbiota and NPC.

Does hyperbaric oxygen therapy have the potential to improve salivary gland function in irradiated head and neck cancer patients?

Following radiotherapy, many patients with osteoradionecrosis suffer from xerostomia, thereby decreasing their quality of life. Patients can develop problems with speech, eating, increased dental caries, dysphagia, fractured dentition, chronic refractory osteomyelitis and osteoradionecrosis. Symptoms associated with salivary gland dysfunction can be severe enough that patients terminate the course of their radiotherapy prematurely due to the decrease in their quality of life. Currently, the only treatments available to patients are palliative. A definitive treatment has yet to be discovered. Head and neck cancers, which comprise 5% of overall cancer treatments, rank 8th most expensive to treat in the United States today. Hyperbaric oxygen is being considered for the therapy of radiated salivary glands because it has been shown to stimulate capillary angiogenesis and fibroplasia in radiation treated tissues. It has been hypothesized that salivary acinar cells undergo apoptosis following radiation therapy. The purpose of this paper is to discuss the mechanisms of salivary gland injury and evaluate whether hyperbaric oxygen therapy improves salivary gland function in patients who develop xerostomia and osteoradionecrosis following head and neck radiation.

The effect of hyperbaric oxygenation on postradiation xerostomia and saliva in patients with head and neck tumours

The study was designed to evaluate the influence of hyperbaric oxygenation (HBO) therapy on salivary gland function and the growth of salivary Streptococcus mutans, Lactobacillus and Candida albicans in patients with head and neck tumours who had undergone radiation therapy. Sixteen patients were included, with radiation doses from 58 to 70 Gy. The first examination was performed at baseline before the first HBO therapy (33.7 ± 9 months after radiation therapy), and the second after 20 daily HBO therapies in a hyperbaric chamber at 2.5 ATA (absolute atmospheres), where patients breathed 100% oxygen for 90 min each day. Measurements of salivary flow, buffer capacity, saliva pH and colony density of S. mutans, Lactobacillus and C. albicans in stimulated saliva were conducted, and xerostomia grade was assessed. Salivary flow increased from 0.20 ± 0.1 to 0.39 ± 0.2 ml/min at the end of HBO therapy (p < 0.001). Salivary pH also increased from 6.0 ± 0.2 to 6.5 ± 0.1 (p < 0.05). The colony density decreased from the time at baseline to the end of HBO therapy for S. mutans (p < 0.001), Lactobacillus (p < 0.05) and the fungus C. albicans (p < 0.05). The xerostomia grade decreased from 2.63 ± 0.2 to 1.94 ± 0.2 after HBO (p < 0.001). There was no significant change in buffer capacity. The increased salivary secretion rate and salivary pH, and decreased S. mutans and Lactobacillus colony density that were observed after HBO therapy may reduce caries progression in those patients.