Inclusion Criteria:

          -  Female, ≥ 18 years of age.

          -  Non-metastatic, histologically or cytologically-confirmed TNBC (defined as ER <1%, PR
             <1%, her-2-neu 0-1+ by IHC or FISH-negative or as per MD discretion), with evidence of
             residual disease in the breast or lymph nodes after neoadjuvant chemotherapy, at the
             time of definitive surgical treatment.

          -  Non-metastatic, histologically or cytologically-confirmed hormone-receptor positive,
             Her2/neu negative breast cancer (defined as ER >1% or PR >1% AND Her-2/neu 0-1+ by IHC
             or FISH-negative, or as per MD discretion), with evidence of residual grade 3 invasive
             breast cancer AND either 1) >5 cm of residual disease in the breast OR 2) ≥ 4 axillary
             LNs in the axilla after neoadjuvant chemotherapy, at the time of definitive surgical
             treatment.

          -  Definitive surgical treatment with breast-conserving surgery or mastectomy and
             axillary lymph node evaluation.

          -  At least 6-month life expectancy, ECOG Performance status < 2.

          -  Willingness to discontinue any cytotoxic chemotherapeutic agents, immunotherapy and
             biologic therapy at least 2 weeks prior to the start of RT.

          -  Adequate organ function (assessed within 30 days prior to initiation of protocol
             treatment, unless otherwise indicated) as follows:

        Hematology

          -  Absolute Neutrophil Count (ANC) ≥1500/mm^3

          -  Platelet Count ≥100,000/mm^3

          -  Hemoglobin ≥9.0 g/dL (after transfusion if required) Renal Function

          -  Creatinine Serum ≤ 1.5 mg/dL or Creatinine Clearance ≥ 45 mL/min^a Hepatic Function

          -  Bilirubin ≤ 1.5 mg/dL

          -  Aspartate Aminotransferase (AST) ≤ 2.5 x ULN^b

          -  Alanine Aminotransferase (ALT) ≤ 2.5 x ULN ULN = upper normal limit of institution's
             normal range

               1. If calculated creatinine clearance is < 45mL/min, a 24-hour urine collection for
                  creatinine clearance may be performed

               2. Subjects with documented Gilbert's disease may have bilirubin up to 2.5 mg/dL

                    -  Negative serum pregnancy test within 14 days prior to study treatment if a
                       woman has child-bearing potential. Subjects of child bearing potential are
                       those who have not been surgically sterilized or have not been free from
                       menses for > 1 year.

                    -  Ability to swallow and retain oral medications.

                    -  Written informed consent obtained from subject and ability for subject to
                       comply with the requirements of the study.

                    -  Female subjects of childbearing potential should be willing to use 2 methods
                       of birth control or be surgically sterile, or abstain from heterosexual
                       activity for the duration of study participation. Should a woman become
                       pregnant while participating on study, she should inform the treating
                       physician immediately.

        Exclusion Criteria:

          -  Gross residual tumor or positive margins after surgery that is un-excised, as
             radiation dose in the study will be limited to 60 Gy.

          -  Complete pathologic response to NAC.

          -  Receipt of PARP inhibitor prior to RT.

          -  Pregnant or expecting to conceive within the projected duration of the trial, starting
             with screening visit through 180 days after the last dose of trial treatment.

          -  Prior history of radiation therapy to the ipsilateral breast and/or regional nodes is
             not allowed (prior RT to other sites is permitted).

          -  Patients with breast augmentation implants are excluded.

          -  History of allergic reactions attributed to compounds of similar chemical or biologic
             composition to rucaparib.

          -  Concomitant anti-neoplastic treatment is not allowed during protocol treatment and
             should be completed at least 2 weeks prior to commencement of protocol treatment, with
             resolution of associated acute toxicities. Bisphosphonates are permitted without
             restriction even during protocol treatment.

          -  Significant comorbidity: Patients with clinically significant and uncontrolled major
             disease or disorder that could exacerbate potential toxicities, confound safety
             assessments, require excluded therapy for management, or limit study compliance.

          -  Ongoing therapy with other investigational agents. Patients may not be receiving any
             other investigational agents.

          -  Unresolved toxicity from other agents. Patients with unresolved CTCAE v4.03 Grade 3 or
             greater toxicity from prior administration of another investigational drug and/or
             anti-cancer treatment are not eligible.