Furthermore, gene expression analysis suggests that rucaparib-induced circadian disruptions extend beyond core-clock genes, affecting key cancer-associated genes such as VEGFA, BRCA1, BRCA2, SIRT1, and TP53. This study highlights the intricate relationship between circadian rhythm alterations and treatment toxicity, emphasising the potential role of chronotherapy in reducing side effects and improving patient outcomes. This evidence concerns the gene BRCA1 and cancer.