Cytogenetic Analysis on the Yields of Chromosomal Aberrations Induced by the Scattered Doses of γ-Radiation

Samit B Kadam,Soorambail K Shyama

doi:10.4172/2155-9619.1000270

Samit B Kadam, Soorambail K Shyama

Open Access

https://doi.org/10.4172/2155-9619.1000270

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Abstract

The present study is undertaken to know the radiation dose-response of chromosomes in the non-target cells, viz. peripheral blood lymphocytes of cancer patients in a context of partial body irradiation. The genotoxic effect of γ- radiation was studied in Head and Neck Squamous Cell Carcinoma (HNSCC) patients exposed to various cumulative doses of 60Co gamma rays during radiotherapy (RT). These patients (P1 to P10) were irradiated for a period of six weeks with a daily fraction of 2 Gy, consecutively for 5 days in every week. The clastogenic effects of radiation in these patients were analysed on every weekend employing chromosomal aberration (CA) assay. Radiosensitivity of these patients were analysed by employing linear regression analysis of the CAs induced by irradiation. Genetic damage observed in all patients on a weekly basis were recorded and analysed at the individual level in comparison with their own pre-therapy baseline data, employing student’s t-test. Dicentrics, centric rings and chromatid breaks were observed as the major kinds of CAs. The total CAs observed were analyzed using two way ANOVA, showed significant (P<0.001) intra and inter-individual variations of the genotoxic effects. Further, a dose dependent increase of cytogenetic damage was observed in the non-target cells viz. lymphocytes. Further, cytogenetic studies in peripheral lymphocytes following gamma radiotherapy of tumors may help to understand the optimum/precise dose of radiation to be employed for RT, may also be useful to predict dosimetry and the possible secondary tumors in irradiated HNSCC patients.

Highlights

Head and neck squamous cell carcinoma (HNSCC) represents the seventh most common cancer globally, with approximately 47,000 new cases reported every year [1]
Genetic damage induced by radiation or other mutagens in nontarget cells is most frequently monitored in peripheral blood leukocytes [5]
Study subjects Ten volunteer HNSCC patients aspiring for RT at Goa Medical

Summary

Introduction

Head and neck squamous cell carcinoma (HNSCC) represents the seventh most common cancer globally, with approximately 47,000 new cases reported every year [1]. The exposure of patients to radiation during radiotherapy is a beneficial use of radiation to improve the health of the individuals, ionizing radiation being a proven mutagen besides damaging killing tumour tissue may induce genetic damage in the neighbouring/adjacent non-target cells. Genetic damage induced by radiation or other mutagens in nontarget cells is most frequently monitored in peripheral blood leukocytes [5]. A key challenge in RT is to maximize radiation doses to cancer cells while minimizing damage to the surrounding non-target healthy tissue. Recent literature in the field of clinical oncology and RT still does not explain sufficiently the question of damages to non-target cells and tissues after chemo-radiation treatment [6,7,8]

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