RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Giving radiation during surgery may be an effective treatment for breast cancer.

PURPOSE: This phase II trial is studying how well radiation therapy works in treating older women who are undergoing surgery for invasive breast cancer.

OBJECTIVES:

Primary

• Determine the feasibility of intraoperative partial breast radiotherapy prior to surgical resection in older women with low-risk early stage primary invasive ductal carcinoma of the breast. Feasibility will be determined by the rate of good/excellent cosmesis, as measured by the Radiation Therapy Oncology Group (RTOG) cosmetic rating scale, in patients treated with this regimen compared with that of patients treated with partial breast brachytherapy in clinical trial RTOG-9517.
• Determine the incidence of grade 3-4 toxicity of this regimen in these patients.
• Determine the rate of ipsilateral breast recurrence, including recurrence within the tumor bed as compared to elsewhere in the breast, in patients treated with this regimen.

Secondary

• Determine the radiation-induced activation of receptors and signal transduction pathways involved in radiation response in patients treated with this regimen.

OUTLINE: This is a non-randomized study.

Patients undergo intraoperative lymphatic mapping and sentinel lymphadenectomy OR standard level I, II axillary dissection to evaluate the lymph nodes followed by intraoperative breast ultrasonography to define the tumor target volume. Patients then undergo intraoperative single-dose partial breast radiotherapy followed by segmental mastectomy (i.e., lumpectomy) of the tumor. Patients with 1 or 2 tumor-involved surgical margins may undergo repeat segmental mastectomy. Patients with > 2 tumor-involved surgical margins undergo mastectomy. Patients determined to have a tumor size > 3 cm or an extensive intraductal component on final pathology evaluation undergo standard external beam radiotherapy after surgery.

After completion of study treatment, patients are followed every 3 months for 2 years, every 6 months for 3 years, and then annually thereafter.

PROJECTED ACCRUAL: A total of 71 patients will be accrued for this study within 2 to 3 years.

DISEASE CHARACTERISTICS:

• Histologically confirmed primary invasive ductal carcinoma of the breast

  • Tumor size ≤ 3 cm
  • No extensive intraductal component
  • Tumor must not be attached to the skin, underlying muscle, or chest wall

• Candidate for breast-conserving therapy, as determined by the surgical and radiation oncologist

  • Tumor amenable to segmental mastectomy (i.e., lumpectomy)

• No bilateral breast cancer

• No clinical or radiographic multifocal disease not amenable to single segmental mastectomy

  • Patients with > 1 tumor mass in the same breast must have only 1 mass that is histologically malignant AND all other masses must be proven histologically benign

• Hormone receptor status:

  • Not specified

PATIENT CHARACTERISTICS:

Age

• 48 and over

Sex

• Female

Menopausal status

• Not specified

Performance status

• 0-2

Life expectancy

• At least 5 years

Hematopoietic

• Not specified

Hepatic

• Not specified

Renal

• Not specified

Other

• Not pregnant

• Fertile patients must use effective contraception

• No collagen vascular disease

• No medical condition that would preclude surgery

• Other prior malignancy allowed provided the following criteria are met:

  • Patient has undergone potential curative therapy for all prior malignancies
  • There is no evidence of any prior malignancy within the past 5 years
  • Patient is deemed to be at low risk for recurrence of prior malignancy, as determined by the treating physician

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• No prior chemotherapy for this malignancy

Endocrine therapy

• Not specified

Radiotherapy

• No prior radiotherapy to the breast

Surgery

• No breast implants

Acute toxicity was evaluated 1 week and 3 months after IORT