Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically confirmed nonlobular invasive breast cancer of one
of the following histologies: Ductal Papillary Medullary Colloid (mucinous) Tubular Stage
I/II (T1-2 N0-1 M0) tumor no greater than 3 cm Prior tylectomy and axillary lymph node
dissection required No more than 3 positive axillary lymph nodes and no extracapsular
extension At least 6 lymph nodes sampled OR Negative sentinal node Surgical clips in place
delineating margins of tylectomy cavity Negative, or close but negative, inked histologic
margins of tylectomy or re-excision specimen Negative margins defined as no tumor at least
2 mm away from the inked margins Close but negative margins defined as tumor within 2 mm
of inked margin Positive margins defined as invasive or noninvasive tumor at inked
resection margins Negative post-tylectomy or post-reexcision mammogram required if disease
presented with malignancy-associated microcalcifications No remaining suspicious
microcalcifications If catheters are placed at time of reexcision, the crieria may not be
feasible but a post brachytherapy mammogram should be obtained as soon as possible No
extensive intraductal carcinoma by the Harvard definition, i.e.: More than 25% of tumor is
ductal carcinoma in situ (DCIS) and there is DCIS in adjacent breast tissue OR Intraductal
carcinoma with microinvasion No proven multicentric carcinoma, i.e.: Tumor in different
quadrants of the breast OR Tumor separated by at least 4 cm The following exclude: Skin or
chest wall invasion Matted or fixed axillary adenopathy Metastatic internal mammary or
supraclavicular nodes Paget's disease of the nipple Previously treated contralateral
breast carcinoma or synchronous bilateral breast carcinoma Hormone receptor status: Not
specified

PATIENT CHARACTERISTICS: Age: Any age Sex: Female Menopausal status: Not specified
Performance status: Not specified Hematopoietic: Not specified Hepatic: Not specified
Renal: Not specified Other: No collagen vascular disease with a c-reactive protein level
above normal or with an active skin rash (e.g., systemic lupus erythematosus, scleroderma,
or dermatomyositis) No coexisting medical condition that reduces life expectancy to less
than 2 years No second malignancy within 5 years except nonmelanomatous skin cancer Not
pregnant or nursing Negative pregnancy test

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior
chemotherapy for breast cancer Planned chemotherapy may begin at least 2 weeks after
removal of brachytherapy catheters Endocrine therapy: Concurrent tamoxifen permitted
Radiotherapy: No prior radiotherapy for breast cancer Surgery: See Disease Characteristics