Investigation of the effect of oral chlorhexidine gel therapy on nasopharyngeal carcinoma patients receiving radiotherapy

Dr Lam, Yu Hang Walter   (Principal Investigator (PI))

Dr Lee Victor Ho Fun   (Co-Investigator)

Dr Pow Edmond Ho Nang   (Co-Investigator)

Dr So Tsz Him   (Co-Investigator)

Professor Botelho Michael George   (Co-Investigator)

18

2017-06-30

2018-12-29

150000

Investigation of the effect of oral chlorhexidine gel therapy on nasopharyngeal carcinoma patients receiving radiotherapy

chlorhexidine, complication, microbiome, nasopharyngeal carcinoma, Quality of life, radiotherapy

Clinical Microbiology,Cancer

201704159001

Seed Fund for Basic Research for New Staff

2016

Completed

Background Nasopharyngeal carcinoma Nasopharyngeal carcinoma (NPC) is the most common head and neck cancer in Hong Kong and in the southeast Asia. In 2013 NPC ranked 10th commonest cancer and accounted for 2.9% of all new cancer cases (Hong Kong Cancer Registry). Each year there will be around 834 newly diagnosed cases in Hong Kong. NPC is a type of squamous cell carcinoma and is more common in male and subjects under age of 55. Radiotherapy is usually part of the standard treatment for this cancer (lasting for around 7 weeks) with the aim to kill radiation-sensitive cancer cells by high energy x-rays. Fortunately, the mortality rate of NPC is low (up to 7.1% in male) and therefore many NPC patients will survive for many years which has long term impact. Despite measures to focus radiation to the cancer cells, this treatment invariably causes damage to healthy tissues along the radiation pathway. This damage has short term and long-term effects and will have impact on patients’ oral health as well as their quality of life (QoL). Common biological side effect associated with radiotherapy includes damage to salivary glands and reduced salivary flow (xerostomia) (Zhang 2015), inflammation of mucosa (mucositis) of the mouth and throat (De Ryck 2015, Sonis 2013, Vasconcelos 2016), difficulty in swallowing (dysplagia) and reduced in body weight. These patients are also highly prone to suffer from dental decay (caries) and jawbone necrosis (osteoradionecrosis). The host biome and health Microbiome/biome is the ecological community of commensal, symbiotic, and pathogenic microorganisms that literally share our body space (Dewhirst 2010, Wade 2013)). It has been found to be important in the homeostasis and maintaining hosts’ health. Oral microbiome has been shown to cause a number of oral infectious diseases, including dental decay, gum disease (periodontitis), root canal (endodontic) infections, dry socket (alveolar osteitis) and tonsillitis. Evidence is accumulating which links oral bacteria to a number of systemic diseases, including cardiovascular disease, stroke, preterm birth, diabetes, and pneumonia. Oral microbiome comprised of over 600 prevalent taxa at the species level. Individuals’ oral microbiomes are highly specific at the species level, although overall the human oral microbiome shows few geographical differences. There are several distinct microbial habitats such as teeth, gum, tongue, cheek, lip and palate in the oral cavity and each biome composition are different as well. Changes of the oral microbiome has been thought to be associated with the development of oral diseases such as dental decay, gum disease and mucosa inflammation. Complex interaction between the commensal microbiota, host susceptibility and environmental factors has been found. While studies found that there was changes in the oral microbiome during receiving radiotherapy (Shao 2011, Hu 2013, Xu 2014, De Ryck 2015, Gao 2015), it was unclear the changes are related to radiotherapy itself or secondary to the associated biological side effect such as dry mouth (Hayashi 2015). Moreover, the changes in the microbiome may be related to the diet (Wade 2013). Peri-and post- radiation management Re-establishment of healthy microbiome is critical to restore oral health of NPC patients. Chlorhexidine is a commonly used antiseptic used in dentistry. Its impact on the dental biofilm (Zaura-Arite 2001) have been reported and it has been used in the treatment of periodontal disease (Quirynen 2000) and dental decay (Emilson 1994). Objectives The aim of this study is to examine the effect of chlorhexidine on the temporal variation of the oral microbiome using next generation sequencing pre- and post radiotherapy and on the side effect of NPC patients undergoing radiotherapy. The dietary profile, salivary parameter, the oral microbiology parameter, severity of symptoms such as difficulty in swallowing and patients’ QoL will be measured. This study will provide a model of re-establish of the dynamic core of biome and restore the host’s oral health. This will lead to improving biome of NPC patients receiving radiotherapy as well as general patients suffering from oral diseases. References De Ryck, Tine, et al. ""Effects of irradiation on epithelial wound healing and microbial diversity in an in-vitro oral mucosa model."" Journal of nuclear medicine and radiation therapy 6.2 (2015). De Ryck, Tine, et al. ""Dynamic shifts in the oral microbiome during radiotherapy."" 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