Oral microbial carriage in oral squamous cell carcinoma patients at the time of diagnosis and during radiotherapy – A comparative study
Introduction
Oral squamous cell carcinoma (OSCC) is a major problem worldwide and more so in India. The incidence rates of cancers of the oral cavity in both males and females in all urban cancer registries of India are among the highest in the world.1 An association between the habit of chewing betel quid with tobacco which is practiced throughout south-east Asia and oral cancer is a known fact.1 The traditional risk factors alone fail to explain the changing epidemiological pattern of increasing incidence in many parts of the world.2 Recently the role of the oral microbial flora has once again been raised. A relationship of OSCC with poor oral hygiene has been well supported due to the presence of poor oral hygiene in head and neck and oesophageal dysplasia/cancer patients.3, 4
Mucositis and salivary gland hypofunction continue to be inevitable outcomes of radiotherapy which is one of the commonly used treatment modality for OSCC.5 The microbes, particularly gram-negative bacteria exacerbate the inflammatory response enhancing the ulceration and pain.6 This makes it difficult to complete the planned course of radiation. Breaks in therapy though promote healing result in tumor progression, with a poorer disease control.7 Additionally, ulceration acts as a portal of entry for microorganisms into the bloodstream leading to local and systemic infections.8, 9 This is important in the scenario wherein already the five year survival is 54%, one of the lowest of the major cancer sites and this has not improved significantly in recent decades.10
Several studies have shown abnormal flora in head and neck radiotherapy patients before and after treatment.11, 12 Furthermore in the past one study has shown better prognosis in OSCC patients who maintained their normal flora.13
The present study attempts to quantify aerobes, anaerobes, coliforms, candida, and gram negative anaerobic bacilli from the saliva samples of oral squamous cell carcinoma during various stages from diagnosis through radiotherapy.
Section snippets
Materials and methods
After obtaining ethical clearance from the concerned institutes and informed consent from the patients, a total of 133 saliva samples were collected from OSCC patients at three different stages: at the time of diagnosis [group III/Lesional group], 14–15th day of radiotherapy [group IV] and 28–30th day of radiotherapy [group V]. Suitable age and sex matched individuals without any chewing habit [group I] and tobacco chewers without any lesion [group II] were taken as controls (Fig. 1).
In
Frequency of isolation (FOI)
Total aerobes, total anaerobes and coliforms were isolated most frequently in lesional group. Candida in radiotherapy group and GNAB in both lesional and radiotherapy groups (Fig. 3). The FOI of total aerobes did not show significant difference between any of the study groups, but total anaerobes (p < 0.0001), candida (p < 0.0001), coliforms (p < 0.0001) and GNAB (p < 0.0001) differed significantly between non-lesional and lesional groups. On comparing non-lesional (p = 0.000), lesional (p < 0.05) and
Discussion
Radiotherapy induces changes in oral microflora; the study attempts to elucidate if this change is the result of the tumor growth, tobacco chewing or is the sole effect of radiotherapy.
The frequency of isolation of total aerobes, total anaerobes and coliforms was the highest in the lesional samples and that of candida in radiotherapy samples.
Conclusion
All the microbial groups studied are supported well by the tumor and irradiated tissue surfaces. While the practice of habits promotes the growth of aerobes and coliforms, the tumor supports anaerobes better. Candidal carriage is definitely promoted by tumor but is more influenced by radiation. Specific increase in E. coli, Pseudomonas aeruginosa, enterobacter species and Klebsiella pneumoniae that are known to be resistant to antimicrobials along with candida in our sequential samples could
Conflict of interest statement
None declared
Funding sources
Self funded.
Acknowledgements
This manuscript was evaluated by Shubhada C and Ajantha GS, Medical Microbiologists, SDM College of Medical Sciences & Hospital, Sattur, Dharwad.
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Present address: Department of Oral & Maxillofacial Pathology and Microbiology, Hitkarini Dental College & Hospital, Jabalpur, India.