PARP1 and digestive system cancer: Thus, BRCA1/2 could be used as clinicopathological biomarkers to evaluate the prognosis of digestive system cancers.739 Moreover, BRCA1/2 mutations are closely related to the progression of multiple cancers, including breast cancer, ovarian cancer, prostate cancer, and pancreatic cancer.733,740 BRCA1/2-deficient cells are highly sensitive to PARP inhibition,741 which is due to inhibition of PARP-dependent SSB repair resulting in the accumulation of DNA lesions (SSBs and DSBs) during replication.733 In conclusion, BRCA1/2 serves as a biomarker for prognosis and treatment response in cancer.