Sequential Evaluation of DNA Damage in Patients with Head and Neck Carcinoma Receiving Radiotherapy
Abstract Background:Head and neck cancers account for about 30% of all cancers in India. The incidence rates of HNSCC in India are30/1, 00,000 for males and 10/1, 00,000 for females. The commonly used treatment modalities include surgery, chemotherapy and radiotherapy. Studies conducted in different types of cancers showed that there is anincreased primary DNA damage even before the commencement of treatment in cancer patients.The treatment modality will further induce DNA damage in addition to the already existing DNA damage.In normal healthy people, DNA damage is effectively repaired. However, in patients with carcinoma, chemo-radiation induced DNA damage is not repaired so effectively. Consequently, there is a high risk of secondary carcinoma by unrepaired damaged DNA.Methodology:In this study, the degree of DNA damage is assessed by comet assay technique in patients with head and neck carcinoma receiving radiotherapy and had complete regression of tumor following radiotherapy. The degree of DNA damage is compared according to the age, gender and associated risk factors of the patients.Results:The comet length parameter of post-RT sample is increased when compared to baseline sample. The head diameter parameter of post-RT sample is increased when compared to baseline sample. The percentage of DNA in head parameter of post-RT sample is decreased when compared to baseline sample. The tail length parameter of post-RT sample is increased when compared to baseline sample. All these findings are indicative of DNA damage following radiotherapy. Consequently, there is a high risk of secondary carcinoma by unrepaired damaged DNA.Conclusion:Patients with locally advanced head and neck carcinoma with complete tumor response following radiotherapy showed a sequential increase in the DNA damage. The co-existing risk factors and old age may increase the baseline DNA damage in the patients with head and neck cancers.