In Vitro Perspective on Hypofractionated Radiotherapy in Breast Cancer

The rising incidence of breast cancer, particularly evident during the COVID-19 pandemic, 19 highlights the need to investigate effective treatment options, especially in resource-limited countries such as those 20 in Sub-Saharan Africa. This study aims to evaluate the in vitro effects of hypofractionated versus conventionally 21 fractionated radiotherapy on various breast cell lines. The responses of breast cell lines including MCF-7 (hormone 22 receptor-positive), MDA-MB-231 (triple-negative), and MCF-10A (non-cancerous) to cobalt-60 γ-rays were 23 assessed. Key radiobiological endpoints included clonogenic survival, adaptive responses, migration, invasion, 24 and cytotoxicity measured through lactate dehydrogenase assays. Findings reveal that α/β ratios for breast cancer 25 cells varied from 2.5 to 5.4 Gy. Notably, hypofractionation reduced survival in hormone receptor-positive cells, 26 while triple-negative cells exhibited increased survival. Additionally, adaptive radiation responses increased 27 viability across all lines, and the non-cancerous (MCF-10A) cell line showed reduced migration post-treatment. 28 These results highlight the importance of personalised radiation therapy, optimising treatment strategies based on 29 specific breast cancer subtypes to potentially improve patient outcomes.