BRCA1 and neoplasm: However, extended treatment of Brca1-deficient tumors with olaparib resulted in greater tumor reduction compared to vehicle treated tumors (2.037±0.282 RTV vs 5.598±2.296 RTV, p<0.01) at 3 compared to 2-week treatment (3.008±0.509 vs 3.710±1.325 RTV, ns), suggesting that a threshold of DNA damage is required for optimal potency.