Multicenter Trial for Eliminating Breast Cancer Surgery or Radiotherapy in Exceptional Responders to Neoadjuvant Systemic Therapy

PRIMARY OBJECTIVES: I. Cohort A1 and A2: To determine the 6 mo, 1, 2, 3, 5, 7, and 10 year biopsy confirmed ipsilateral breast tumor recurrence rate (IBTR, invasive and/or in situ) among patients who do not undergo surgery. II. Cohort B: To determine the pCR rate 6 or 12 months after radiation therapy based on image-guided biopsy. III. Cohort C: To determine the 6 mo, 1, 2, 3, 5, 7 and 10-year ipsilateral breast tumor recurrence rate among patients who undergo surgery alone without radiation. SECONDARY OBJECTIVES: I. Cohort B: To determine the 6 mo, 1, 2, 3, 5, 7 and 10--year biopsy confirmed ipsilateral breast tumor recurrence rate (IBTR, invasive and/or in situ) among patients who do not undergo surgery. II. To determine the number (%) of patients where final biopsy reveals residual disease and quantify the residual disease (residual cancer burden, RCB) determined by routine pathologic examination of surgery specimens. III. To assess baseline, 6 months, 1, 3, 5, 7, and 10 years decisional comfort of clinical trial participation using the Decisional Regret Scale (DRS). IV. To determine patient-reported cosmetic outcome, breast pain, and functional status using the Breast Cancer Treatment Outcomes Scale (BCTOS) at baseline, 6 months, 1, 3, 5, 7, and 10 years. V. To determine the 6 mo, 1, 2, 3, 5, 7, and 10 years incidence of ipsilateral breast and nodal recommendation and performance of biopsy based on breast imaging follow-up. VI. Correlate "liquid biopsy" analyses (after standard routine NST, 6 months and one year post-radiotherapy or surgery) among protocol participants with pCR, utilizing circulating tumor cells (CTCs) and circulating tumor-DNA (ctDNA). VII. Among patients who decide to proceed with routine surgery, record the results of final biopsy compared with routine pathologic examination of surgery specimens. VIII. To determine patient-reported quality of life using the FACT B+4 instrument at baseline, 6 months, 1, 3, 5, 7, and 10 years after treatment. IX. To explore if radiation genomic sensitivity scores and Oncotype performed on the initial diagnostic core biopsy specimen correlate with pCR rates in Cohort B. X. To determine if changes in blood-based RNA Sequencing are elicited with radiation in Cohort B, measured at baseline, at the first 4-6 week follow-up after radiation, and at the 6 month post-radiation follow-up. XI. In Cohort B to determine the 3-year rate of tumor control/ progression free survival (PFS). XII. In Cohort C/D to determine whether nanomechanical biomarkers or quantification of stromal and tumor TILS can predict for low risk of local recurrence in exceptional responders who omit radiation therapy. XIII. In Cohorts A/B/C/D: To record 6 mo, 1, 2, 3, 5, 7, and 10 year breast cancer disease-free and overall survival. XIV. In Cohort D: Correlate nanomechanical biomarker analyses with pCR and/or local recurrence in patients with triple negative or her-2 positive breast cancer treated with lumpectomy +/- radiation. OUTLINE: For Cohorts A, within 12 weeks of completing neoadjuvant systemic therapy, patients undergo whole breast irradiation over 15-25 fractions on consecutive days. Patients then undergo external beam radiation therapy (EBRT) boost over 7 fractions on consecutive days beginning the day following completion of whole breast irradiation. For Cohort B, patients will receive 3 months of neoadjuvant endocrine therapy, after which they will receive ablative partial breast irradiation over 5 fractions. Patients will then continue with endocrine therapy. After completion of study treatment, patients are followed up every 6 months for 10 years.