ESTRO meets Asia 2024 - Abstract Book

S51

Interdisciplinary – Biomarkers

ESTRO meets Asia 2024

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Digital Poster

Biodosimetric estimate of radiosensitisation using cisplatin in H&N cancer patients undergoing RT.

Nayan Agarwal 1 , Arun K Rathi 1 , Palak N Agarwal 2 , Sunil K Polipalli 3 , Ankur Jindal 3 , Seema Kapoor 3

1 Radiation Oncology, MAMC & Lok Nayak Hospital, New Delhi, India. 2 Public Health Administration, NHSRC, New Delhi, India. 3 Pediatric Research and Genetic Lab, MAMC & Lok Nayak Hospital, New Delhi, India

Purpose/Objective:

Background

Biodosimetry is the quantification of absorbed radiation dose using biological material obtained from an exposed individual. Dicentric chromosome (DC) Assay has become the ‘gold standard’ for cytogenetic biodosimetry due to its reproducibility, specificity (low baseline rates) and sensitivity to low doses. The radiosensitizer role of cisplatin is well established but a quantitative, biological assessment of the same in vivo with a biomarker like DC assay can provide a definitive estimation of its effect.

Objective

To evaluate and compare the number of DC aberrations formed in peripheral blood lymphocytes of Head and Neck Cancer (HNC) patients undergoing radiotherapy alone (RT alone) versus cisplatin-based concomitant chemoradiation (CTRT).

Material/Methods:

This prospective, observational, analytical study was conducted from 2018-2022 in the Department of Radiation Oncology and Genetics Lab of a tertiary-care teaching hospital after approval from the Institutional Ethics Committee. Biodosimetric analysis was done weekly in a total of 97, demographically similar patients recruited into the study undergoing RT alone (n=44) vs. CTRT (n=53). The patients received RT to a total dose of 50-70Gy via Cobalt-60 teletherapy using standard fractionation. All platinum eligible patients were given concomitant Cisplatin via weekly intravenous infusion 1 hour before radiation at a dose of 40mg/m 2 /week. The yield of DCs was measured in blood samples taken before starting treatment and during RT course from blood sample drawn two hours after RT. Phytohemagglutinin stimulated lymphocytes were cultured using heparinized blood in RPMI-1640 medium supplemented with fetal bovine serum. Cells were arrested at metaphase using demecolcine, harvested by centrifugation, mounted and stained with Giemsa. Cytogenetic analysis was performed by analyzing at least 100 metaphases with well-spread chromosomes. DC and acentric fragments were identified and recorded. To