Biological Effects of Radiation Therapy on Cancer Cells

Background: Radiation therapy damages tumour cells' DNA and induces apoptosis, a common cancer treatment. The biological response to radiation depends on tumour type, genetics, and microenvironment. This study examines radiation therapy's effects on cancer cells and tumour regression and survival. Methods: A prospective observational study of 150 radiation therapy patients was done at Patna Medical College and Hospital (PMCH) from April 2022 to March 2024. The biological response was evaluated using ?-H2AX DNA damage markers, caspase-3 apoptosis markers, and tumour regression rates. We also examined treatment-related toxicity and survival. Results: Of the patients, 85% demonstrated a strong DNA damage response (?-H2AX expression) and 70% indicated enhanced apoptosis (caspase-3 activation). Head and neck (75%) and cervical (70%) malignancies had the highest tumour regression rates (68%). Patients had 40% treatment-related toxicities, 10% of which were severe (Grade 3–4). PFS was 65% and OS was 72% at 1 year. Conclusion: Radiation therapy effectively induces DNA damage and apoptosis, leading to significant tumor regression. However, tumor resistance remains a challenge, necessitating further research into radiosensitizers and combination therapies to enhance treatment efficacy. Keywords: Radiation therapy, DNA damage, apoptosis, tumor regression, survival outcomes