This phase IV trial studies the side effects of intraoperative radiation therapy and how well it works in treating patients with breast cancer undergoing breast-conserving surgery. Delivering radiation one time to the area where the tumor was removed while the patient is still in the operating room may kill any residual tumor cells and may be as effective as standard radiation therapy in patients with early stage breast cancer.

PRIMARY OBJECTIVES:

I. To establish eligibility criteria based on previously published trials and studies in order to allow women who meet these criteria to receive intraoperative radiation therapy (IORT) on an Institutional Review Board (IRB)-approved protocol.

II. To systematically collect and assess acute and long-term toxicity and outcomes in larger cohort of patients.

III. To study the efficacy and toxicity of breast radiotherapy given intra-operatively as a single fraction after breast conserving surgery, with or without whole breast radiation, as indicated by pathologic risk factors, in women with early stage breast cancer.

IV. In-breast local failure and patterns of in-breast failure. V. Ipsilateral regional nodal failure. VI. Toxicity and morbidity. VII. Relapse-free survival. VIII. Overall survival.

OUTLINE:

Patients undergo IORT in a single fraction over 15-40 minutes at the time of standard of care lumpectomy.

After completion of study treatment, patients are followed up within 6 weeks and then every 6 months for 3 years and yearly for 2 years.

Inclusion Criteria:

• Suitable for breast conserving surgery
• T1 and T2 (< 3.5 cm), N0, M0

Exclusion Criteria:

• Axillary lymph node positive breast cancer

• Tumor size > 3.5 cm

• Extensive intraductal component (EIC >= 25% of the lumpectomy specimen involved with ductal carcinoma in situ), as assessed on surgical pathologic lumpectomy specimen

• Multicentric cancer in the same breast as diagnosed by clinical examination, mammography, ultrasound; magnetic resonance imaging (MRI) or pathologic assessment, not amenable to excision with negative margins with a single lumpectomy

• Inability to assess pathologic margin status

• Synchronous bilateral breast cancer at the time of diagnosis

• Ipsilateral breast had a previous cancer and/or prior in-field radiation

• Patients known to have BRCA1/2 gene mutations (testing for gene mutations is not required)

• Patients undergoing primary systemic treatment (hormones or chemotherapy) as initial treatment with neoadjuvant reducing tumor size

• Previous history of malignant disease does not preclude entry if the expectation of relapse-free survival at 10 years or greater

• Any factor included as exclusion criteria in the participating center's treatment policy statement

• Additional exclusion criteria for University of California San Francisco (UCSF) (as laid out in the Treatment Policy):

  • Patients under the age of 50
  • Estrogen receptor negative (as defined in Treatment Policy under "Pathology")
  • Human epidermal growth factor receptor 2 (HER2) positive (as defined in Treatment Policy under "HER2")
  • Lymphovascular invasion
  • High grade
  • Tumors > 3 cm
  • Node positive patients
  • Prior chemotherapy or hormone therapy