RATIONALE: Drugs used in chemotherapy, such as capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high energy x-rays to kill tumor cells. Capecitabine may also make tumor cells more sensitive to radiation therapy. Giving radiation together with capecitabine after surgery may kill any remaining tumor cells.

PURPOSE: This phase II trial is studying the side effects and how well giving capecitabine together with radiation therapy works in treating patients with nonmetastatic breast cancer.

OBJECTIVES:

Primary

• To determine the safety and feasibility of concurrent capecitabine and standard external-beam irradiation in patients with high-risk early stage breast cancer.

Secondary

• To determine the effects of concurrent treatment on cosmesis and wound healing at 1 year.
• To determine the short-term (1-year) risk of recurrence of breast cancer in these patients.

OUTLINE: This is a multicenter study.

Patients undergo external-beam radiotherapy once daily, 5 days a week and concurrently receive oral capecitabine twice daily, 5 days a week Monday through Friday, for approximately 6-7 weeks.

After completion of study therapy, patients are followed at approximately 1 week, 1 month, 6 months, and 12 months.

DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed invasive adenocarcinoma of the breast, meeting 1 of the following high-risk criteria:

  • T3 or T4 primary tumor
  • 4 or more involved axillary lymph nodes (N2 nodal stage)

• Completed surgical excision

  • No immediate reconstruction with autologous flap reconstruction

    • Patients having tissue expanders or implants placed prior to radiation may be enrolled at the physician's discretion

• No residual breast cancer

  • Microscopically positive margins are allowed if a re-excision is not felt to be clinically justified

• Candidate for radiotherapy

  • Must not require bilateral radiotherapy

• No metastatic (stage IV) breast cancer by AJCC staging criteria

• Hormone receptor status not specified

• No CNS disorders

PATIENT CHARACTERISTICS:

• Life expectancy ≥ 6 months

• Karnofsky performance status 70-100%

• Menopausal status not specified

• Ambulatory

• Hemoglobin > 9 g/dL

• Platelet count > 100,000/mm³

• ANC > 1,500/mm³

• Serum AST, ALT, and alkaline phosphatase ≤ 2 times upper limit of normal (ULN)

• Total bilirubin normal

• Creatinine clearance > 50 mL/min

• Negative pregnancy test

• Not pregnant or nursing

• Fertile patients must use effective contraception during study and for 30 days after the last study drug administration

• No serious, uncontrolled, concurrent infection(s)

• No diabetes with current or history of delayed wound healing or skin ulcers

• No autoimmune connective tissue disorder

• No prior unanticipated severe reaction to fluoropyrimidine therapy, known sensitivity to 5-fluorouracil, or known dihydropyrimidine dehydrogenase (DPD) deficiency

• No other carcinomas within the last five years except cured non-melanoma skin cancer and in-situ cervical cancer

• No clinically significant cardiac disease (e.g., congestive heart failure, symptomatic coronary artery disease, or cardiac arrhythmias not well controlled with medication) or myocardial infarction within the last 12 months

• No other serious uncontrolled medical conditions that the investigator feels might compromise study participation, including any of the following:

  • Uncontrolled seizures
  • Psychiatric disability judged by the investigator to be clinically significant

• Physically intact upper gastrointestinal tract

• No malabsorption syndrome

• No uncompensated coagulopathy

• No patients whose breast size or body contour puts them at increased risk for skin desquamation from standard radiotherapy

• Able to read and speak English

PRIOR CONCURRENT THERAPY:

• Fully recovered from surgery and chemotherapy with completely healed surgical wounds

• At least 4 weeks since completion of prior chemotherapy regimen, excluding trastuzumab (Herceptin®)

  • Concurrent trastuzumab allowed at the physician's discretion

• More than 4 weeks since prior participation in any investigational drug study

• At least 4 weeks since prior and no concurrent sorivudine or brivudine

• More than 2 weeks since prior major surgery

• No prior capecitabine

• No prior radiotherapy to the chest or ipsilateral lymphatics

• No concurrent hormonal therapy during course of chemotherapy or radiation therapy

• No concurrent allopurinol or cimetidine

• Concurrent coumadin is allowed

Female only study