Inclusion Criteria:

   - Histologically confirmed non-metastatic primary invasive adenocarcinoma of the breast
   that is one of the following phenotypes:

      1. Triple negative breast cancer defined as: ER and PgR negative AND HER2 negative
      (not eligible for anti-HER2 therapy)

      2. ER and/or PgR positive, HER2 negative

   - Documented germline mutation in BRCA1 or BRCA2 that is predicted to be deleterious or
   suspected deleterious (known or predicted to be detrimental/lead to loss of function).

   - Completed adequate breast and axilla surgery.

   - Completed at least 6 cycles neoadjuvant or adjuvant chemotherapy containing
   anthracyclines, taxanes or the combination of both. Prior platinum as potentially
   curative treatment for prior cancer (e.g. ovarian) or as adjuvant or neoadjuvant
   treatment for breast cancer is allowed.

   - ECOG 0-1.

Exclusion criteria:

   - Any previous treatment with a PARP inhibitor, including olaparib and/or known
   hypersensitivity to any of the excipients of study treatment.

   - Patients with second primary malignancy. EXCEPTIONS are:

      1. adequately treated non-melanoma skin cancer, curatively treated in situ cancer of
      the cervix, Ductal Carcinoma in situ (DCIS) of the breast, stage 1 grade 1
      endometrial carcinoma

      2. other solid tumours and lymphomas (without bone marrow involvement) diagnosed ≥ 5
      years prior to randomisation and treated with no evidence of disease recurrence
      and for whom no more than one line of chemotherapy was applied.

   - Concomitant use of known strong CYP3A inhibitors (e.g., itraconazole, telithromycin,
   clarithromycin, protease inhibitors boosted with ritonavir or cobicistat, indinavir,
   saquinavir, nelfinavir, boceprevir, telaprevir) or moderate CYP3A inhibitors (e.g.,
   ciprofloxacin, erythromycin, diltiazem, fluconazole, verapamil). The required washout
   period prior to starting study treatment is 2 weeks. Concomitant use of known strong
   (e.g., phenobarbital, enzalutamide, phenytoin, rifampicin, rifabutin, rifapentine,
   carbamazepine, nevirapine and St John's Wort) or moderate CYP3A inducers (e.g.,
   bosentan, efavirenz, modafinil). The required washout period prior to starting study
   treatment is 5 weeks for enzalutamide or phenobarbital and 3 weeks for other agents.

   - Evidence of metastatic breast cancer