This is a phase III, randomized, open label, multicenter, controlled trial of niraparib versus physician's choice in previously-treated, HER2 negative, germline BRCA mutation-positive breast cancer patients. Niraparib is an orally active PARP inhibitor. Niraparib (in a 2:1 ratio) will be administered once daily continuously during a 21-day cycle. Physician's choice will be administered on a 21-day cycle. Health-related quality of life will be measured. The safety and tolerability will be assessed by clinical review of adverse events (AEs), physical examinations, electrocardiograms (ECGs), and safety laboratory values.