Inclusion Criteria:

          -  Patients with histologically confirmed non-metastatic invasive breast cancer who will
             be undergoing neoadjuvant chemotherapy and have persistent disease at time of
             definitive surgery

               -  Tumors must have ER/PR/HER2 status reported by available pathology report(s)

               -  Both triple negative and hormone receptor positive patients are eligible for
                  enrollment

          -  Completion of neoadjuvant chemotherapy

               -  May not include capecitabine or 5-FU containing regimens

               -  Resolution of adverse events from neoadjuvant chemotherapy including
                  biochemical/hematologic to CTCAE v5.0 grade 1 or below (except alopecia) prior to
                  initiation of study therapy

               -  Recovery time between surgery and study therapy ≥ 4 weeks.

          -  Persistent invasive disease following neoadjuvant chemotherapy in either the breast,
             lymph node, or both ). Any residual tumor; lack of complete pathologic response.

          -  Patients planning to receive adjuvant radiation to the breast and/or regional nodes.

          -  Patients planning to receive capecitabine per the treating physician

        Patients already receiving capecitabine as adjuvant therapy are eligible to enroll in this
        study, provided adverse events deemed by the treating physician as possibly, probably or
        definitely related to adjuvant capecitabine prior to study therapy have resolved to CTCAE
        v.5.0 grade 1 or below (except alopecia), and provided duration of planned capecitabine
        includes entire duration of planned radiotherapy.

          -  ECOG performance status 0 or 1

          -  Tamoxifen: patients who have received Tamoxifen as chemoprevention are still eligible.

        Endocrine receptor therapies (Hormone receptor inhibitors) may not be given with study
        treatment.

          -  . Patients who have had radiation to the contralateral breast are eligible.

          -  Ability to understand and the willingness to sign a written informed consent document.

        Exclusion Criteria:

          -  Pregnant or lactating females. Women who are pregnant or who become pregnant are
             excluded from this study because capecitabine is a chemotherapeutic agent with the
             potential for teratogenic or abortifacient effects. Because there is an unknown but
             potential risk for adverse events in nursing infants secondary to treatment of the
             mother with capecitabine, breastfeeding should be discontinued if the mother is
             treated with capecitabine. These potential risks may also apply to radiotherapy used
             in this study.

          -  Serious medical or psychiatric illness that in the judgement of the treating physician
             places the patient at risk & would limit compliance with the study requirements.

          -  Inability to swallow or retain whole pills.

          -  Patients with known or suspected allergy to capecitabine or 5-FU.

          -  Contraindications to capecitabine or radiotherapy as determined by the treating
             physician including severe renal impairment (GFR < 30).

          -  Prior radiation to the ipsilateral breast.