Inclusion Criteria:

          -  The patient must have signed and dated an Institutional Review Board (IRB)-approved
             consent form that conforms to federal and institutional guidelines

          -  The patient must have an Eastern Cooperative Oncology Group (ECOG) performance status
             of 0 or 1

          -  Patients must have had ER analysis performed on the primary breast tumor collected
             prior to neoadjuvant therapy according to current American Society of Clinical
             Oncology (ASCO)/College of American Pathologists (CAP) guideline recommendations for
             hormone receptor testing; if negative for ER, assessment of progesterone receptor
             (PgR) must also be performed according to current ASCO/CAP Guideline Recommendations
             for hormone receptor testing. Patients who have a primary tumor that is hormone
             receptor-positive or hormone receptor-negative are eligible.

          -  Patients must have had HER2 testing performed on the primary breast tumor collected
             prior to neoadjuvant chemotherapy according to the current ASCO/CAP guideline
             recommendations for human epidermal growth factor receptor 2 testing in breast cancer;
             patients who have a primary tumor that is HER2-positive, HER2-equivocal, or
             HER2-negative are eligible

          -  Patients must have had a biopsy marker placed within the tumor bed with imaging
             confirmation (preferably mammogram but ultrasound or magnetic resonance imaging [MRI]
             is acceptable) of marker placement prior to neoadjuvant chemotherapy

          -  Patients with operable focal or multifocal (T1-T3, stage II or III invasive ductal
             carcinoma [all receptor phenotypes]), and who have completed neoadjuvant chemotherapy
             with a clinical complete response (by clinical examination)

          -  Patients with synchronous bilateral breast cancer are eligible if at least one of the
             synchronous breast cancers has a cCR, and the side with a cCR meets criteria.
             (Patients with previous contralateral invasive breast cancer treated with anti-cancer
             therapy are eligible.)

          -  Patients must have achieved a complete or near complete radiologic tumor response on
             breast imaging with mammogram, ultrasound, and MRI during or after completion of
             appropriate neoadjuvant chemotherapy defined as:

               -  Mammogram with malignant appearing calcification or mass ≤ 1 cm; or

               -  Ultrasound with a hypoechoic area ≤ 2 cm; or

               -  Breast MRI not demonstrating a residual mass with rapid rise and washout type III
                  kinetics.

          -  At the time of consent, the patient's intent must be to undergo breast conserving
             therapy.

          -  Patient must be able to undergo stereotactic-vacuum-assisted breast biopsy with clip
             placement after completion of neoadjuvant chemotherapy. (The patient must be enrolled
             on the study before performing the post-neoadjuvant stereotactic-vacuum-assisted
             breast biopsy.)

          -  Patient must have completed neoadjuvant chemotherapy.

          -  Patients with HER2-positive tumors must have received neoadjuvant anti-HER2 therapy
             (either with all or with a portion of the neoadjuvant chemotherapy regimen), unless
             medically contraindicated.

          -  Patients treated with PD-1 or PD-L1 inhibitors, CDK 4/6 inhibitors, or other
             immune-based therapy are eligible.

        Exclusion Criteria:

          -  T4 tumors including inflammatory breast cancer

          -  Patients with distant metastatic disease

          -  Lumpectomy performed prior to study entry

          -  Patients with any history of prior radiation therapy in the affected breast

          -  Patients with a prior history of ipsilateral invasive breast cancer; (patients with
             previous ipsilateral/contralateral DCIS or previous contralateral invasive breast
             cancer treated with anti-cancer therapy are eligible)

          -  Patients with invasive lobular carcinoma

          -  Patients who have multicentric disease

          -  Patients treated with neoadjuvant hormonal therapy only are not eligible

          -  Patients who are medically unfit to undergo surgical resection

          -  Patients without breast biopsy marker documented by imaging at tumor bed site prior to
             initiation of neoadjuvant therapy

          -  Patients with one or more of the following imaging criteria from any of the 3 imaging
             modalities after completion of NCT demonstrating incomplete radiologic response are
             not eligible:

               -  Mammogram with malignant appearing calcifications or mass > 1 cm; or

               -  Ultrasound with a hypoechoic area > 2 cm; or

               -  Breast MRI demonstrating a residual mass with rapid rise and washout type III
                  kinetics.

          -  Psychiatric or addictive disorders or other conditions that, in the opinion of the
             investigator, would preclude the patient from meeting the study requirements or
             interfere with interpretation of study results

          -  Pregnancy or lactation at the time of study registration; (Note: Pregnancy testing
             according to institutional standards for women of childbearing potential must be
             performed within 2 weeks prior to study registration.)