Radiation Therapy Using Gold Markers in Treating Women With Early-Stage Breast Cancer

DISEASE CHARACTERISTICS: Inclusion criteria: * Histologically confirmed ductal carcinoma in situ or invasive carcinoma of the breast (including ductal, medullary, papillary, colloid \[mucinous\], or tubular histologies) meeting all of the following criteria: * AJCC stage 0, I, or II (Tis, T1N0, or T2N0) disease with a lesion ≤ 3 cm treated with lumpectomy and either sentinel node biopsy or axillary dissection (if invasive carcinoma is present) * Unifocal breast cancer (i.e., single focus that can be encompassed by one lumpectomy) * Underwent or plan to undergo lumpectomy with placement of gold fiducial markers (markers placed concurrently with the surgery or on a later date) * Patients who has underwent lumpectomy must meet all of the following criteria: * Must be enrolled between 14-60 days from date of last surgery, and radiation must start within 15-80 days of date of last surgery * Four to six gold fiducial markers placed in the tumor bed, delineating the margins of the lumpectomy cavity * Negative, inked histologic margins of lumpectomy (\> 1 mm) or re-excision specimen to be confirmed prior to radiation * Margins are unacceptable if there is invasive or non-invasive tumor within 1 mm of the inked margin * Negative post-excision mammography if malignancy-associated microcalcifications were initially present * Hormone receptor status not specified Exclusion criteria: * Evidence of suspicious microcalcifications in the breast prior to the st…