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NSABP-B51: A randomized, phase III clinical trial evaluating post-mastectomy chest wall and regional nodal XRT and post-lumpectomy regional nodal XRT in patients with positive axillary nodes before neoadjuvant chemotherapy, who convert to pathologically negative axillary nodes after neoadjuvant chemotherapy


This randomized phase III trial studies standard or comprehensive radiation therapy in treating patients with early-stage breast cancer who have undergone surgery. Radiation therapy uses high-energy X-rays to kill tumor cells. It is not yet known whether comprehensive radiation therapy is more effective than standard radiation therapy in treating patients with breast cancer.


Accepting new patients

Primary Study Objective(s)

The primary objective of this study is to evaluate whether the addition of chest wall plus regional nodal XRT after mastectomy or breast plus regional nodal XRT after breast-conserving surgery will significantly reduce the rate of events for invasive breast cancer recurrence-free interval (IBC-RFI) in patients who present with histologically positive axillary nodes but convert to histologically negative axillary nodes following neoadjuvant chemotherapy.

Core eligibility

Note: This is only a partial list of eligibility criteria.

Including patients who: 

  • Have signed and dated an Institutional Review Board (IRB)-approved consent form that conforms to federal and institutional guidelines
  • Have an Eastern Cooperative Oncology Group (ECOG) performance standard of 0 or 1
  • Have clinically T1-3, N1 breast cancer at the time of diagnosis (before neoadjuvant therapy); clinical axillary nodal involvement can be assessed by palpation, ultrasound, CT scan, magnetic resonance imaging (MRI), positron emission tomography (PET) scan, or PET/CT scan
  • Have had pathologic confirmation of axillary nodal involvement at presentation (before neoadjuvant therapy) based on either a positive fine needle aspirate (FNA) (demonstrating malignant cells) or positive core needle biopsy (demonstrating invasive adenocarcinoma); the FNA or core needle biopsy can be performed either by palpation or by image guidance; documentation of axillary nodal positivity by sentinel node biopsy (before neoadjuvant therapy) is not permitted
  • Have had estrogen receptor (ER) analysis performed on the primary breast tumor before 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 (
  • Have had HER2 testing performed on the primary breast tumor before 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 either HER2-positive or HER2-negative are eligible
  • Have completed a minimum of eight weeks of standard neoadjuvant chemotherapy consisting of an anthracycline and/or taxane-based regimen
  • Have received a maximum of 12 weeks of chemotherapy after surgery (if treatment delays occur, chemotherapy must be completed within 14 weeks); the dose and schedule of the adjuvant chemotherapy are at the investigator's discretion; note: it is preferred that all intended chemotherapy be administered in the neoadjuvant setting
  • Have received neoadjuvant anti-HER2 therapy (either with all or with a portion of the neoadjuvant chemotherapy regimen), unless medically contraindicated (for patients with HER2-positive tumors)
  • Have removed axillary nodes histologically free from cancer at the time of definitive surgery; acceptable procedures for assessment of axillary nodal status at the time of surgery include:
    • Axillary node dissection
    • Sentinel node biopsy alone or
    • Sentinel node biopsy followed by axillary node dissection
    • Note: Patients are eligible whether there is residual invasive carcinoma in the surgical breast specimen or whether there is evidence of pathologic complete response; patients who are found to be pathologically node-positive at the time of the surgery, based on sentinel node biopsy alone, are candidates for A011202, a study developed by the Alliance in Oncology, an NCI Cooperative Group; if A011202 is open at the investigator's institution, patients should be approached about participating in the in A011202 study
  • Have pathologic staging of ypN0(i+) or ypN0(mol+); (note: post-neoadjuvant therapy is designated with a "yp" prefix)
  • Have undergone either a total mastectomy or a lumpectomy
  • Have undergone a lumpectomy and the margins of the resected specimen or re-excision are histologically free of invasive tumor and DCIS as determined by the local pathologist; additional operative procedures may be performed to obtain clear margins; if tumor is still present at the resected margin after re-excision(s), the patient must undergo total mastectomy to be eligible; (patients with margins positive for lobular carcinoma in situ [LCIS] are eligible without additional resection)
  • Have margins histologically free of residual (microscopic or gross) tumor, in patients who undergo mastectomy
  • Have an interval of no more than 70 days between the last surgery for breast cancer (including re-excision of margins) and randomization; also, if adjuvant chemotherapy was administered, the interval between the last chemotherapy treatment and randomization must be no more than 70 days
  • Have recovered from surgery with the incision completed healed and no signs of infection
  • Have resolved chemotherapy-related toxicity that may interfere with delivery of radiation therapy, if adjuvant chemotherapy was administered

Excluding patients who:

  • Have definitive clinical or radiologic evidence of metastatic disease
  • Have T4 tumors, including inflammatory breast cancer
  • Have documentation of axillary nodal positivity before neoadjuvant therapy by sentinel node biopsy alone
  • Have N2 or N3 disease detected clinically or by imaging
  • Have histologically positive axillary nodes post neoadjuvant therapy
  • Have microscopic positive margins after definitive surgery
  • Have synchronous or previous contra-lateral invasive breast cancer or DCIS; (patients with synchronous and/or previous contra-lateral LCIS are eligible)
  • Have any prior history, not including the index cancer, of ipsilateral invasive breast cancer or ipsilateral DCIS treated with radiation therapy; (patients with synchronous or previous ipsilateral LCIS are eligible)
  • Have a history of non-breast malignancies (except for in situ cancers treated only by local excision and basal cell and squamous cell carcinomas of the skin) within five years prior to randomization
  • Have had any radiation therapy for the currently diagnosed breast cancer prior to randomization
  • Have any continued use of sex hormonal therapy, e.g., birth control pills, ovarian hormone replacement therapy; patients are eligible if these medications are discontinued prior to randomization
  • Have had prior breast or thoracic radiation therapy for any condition
  • Have active collagen vascular disease, specifically dermatomyositis with a creatinine phosphokinase (CPK) level above normal or with an active skin rash, systemic lupus erythematosus, or scleroderma
  • Have pregnancy or lactation at the time of study entry; (note: pregnancy testing must be performed within two weeks prior to randomization according to institutional standards for women of child-bearing potential)
  • Have other non-malignant systemic disease that would preclude the patient from receiving study treatment or would prevent required follow-up
  • Have psychiatric or addictive disorders or other conditions that, in the opinion of the investigator, would preclude the patient from meeting the study requirements

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Principal Investigator(s)

Stephen P. Ray
Marnee Spierer
Steven B. Standiford