Doxorubicin and Cyclophosphamide Followed By Trastuzumab, Paclitaxel, and Lapatinib in Treating Patients With Early-Stage HER2-Positive Breast Cancer That Has Been Removed By Surgery

DISEASE CHARACTERISTICS:

• Histologically confirmed diagnosis of early-stage breast cancer
• HER2 positive by immunohistochemistry (IHC) (3+) or fluorescent in situ hybridization (FISH)
• Ductal carcinoma in situ (DCIS) components should not be counted in the determination of degree of IHC staining or FISH amplification
• No locally advanced tumors (i.e., T4) at diagnosis, including the following:
• Tumors fixed to chest wall
• Peau d'orange
• Skin ulcerations or nodules
• Clinical inflammatory changes (e.g., diffuse brawny cutaneous induration with an erysipeloid edge)
• Has undergone mastectomy or lumpectomy with axillary node or sentinel node dissection within the past 84 days
• Patients who have undergone a mastectomy must meet the following criteria:
• No evidence of gross or microscopic tumor (i.e., invasive DCIS) at the surgical resection margins noted in final surgery or pathology reports
• Patients with close margins are eligible
• Radiation therapy is required for 4 or more positive lymph nodes and must be started after completion of chemotherapy
• Patients who have undergone a lumpectomy with axillary node or sentinel node dissection must meet the following criteria:
• No evidence of invasive cancer or DCIS at the surgical resection margins
• No gross residual adenopathy
• Planning to undergo radiation therapy to the breast with or without regional lymphatics after completion of chemotherapy
• No active hepatic or biliary disease
• Patients with liver metastases, stable chronic liver disease, Gilbert's syndrome, or asymptomatic gallstones are eligible
• Hormone receptor status:
• Estrogen receptor and progesterone receptor status known

PATIENT CHARACTERISTICS:

• Male or female
• Menopausal status not specified
• ECOG performance status 0-2
• Absolute neutrophil count ≥ 1,500/mm³
• Platelet count ≥ 100,000/mm³
• Hemoglobin ≥ 10.0 g/dL
• Bilirubin ≤ 1.5 times upper limit of normal (ULN)
• AST and ALT ≤ 2.5 times ULN
• Alkaline phosphatase ≤ 2.5 times ULN
• Creatinine normal OR creatinine clearance ≥ 60 mL/min
• LVEF ≥ 50% by MUGA scan or echocardiogram
• Able to complete questionnaire(s) by themselves or with assistance
• Able and willing to provide blood and tissue samples
• No known sensitivity to benzyl alcohol
• No sensory neuropathy ≥ grade 2
• No active cardiac disease, including any of the following:
• Myocardial infarction within the past 6 months
• Prior or concurrent congestive heart failure
• Prior or concurrent arrhythmia or cardiac valvular disease requiring medications or that is clinically significant
• Uncontrolled hypertension, defined as diastolic blood pressure (BP) >100 mm Hg or systolic BP > 200 mm Hg on 2 separate occasions ≥ 14 days apart
• Clinically significant pericardial effusion
• Prior or concurrent uncontrolled or symptomatic angina
• Other cardiac condition that, in the opinion of the treating physician, would put the patient at hazardous risk
• No history of allergic reactions attributed to compounds of similar chemical or biologic composition as lapatinib ditosylate
• No uncontrolled intercurrent illness including, but not limited to, the following:
• Ongoing or active infection
• Psychiatric illness or social situations that would preclude study compliance
• Able to swallow and retain oral medication
• No history of gastrointestinal (GI) disease resulting in an inability to take oral medication, including any of the following:
• Malabsorption syndrome
• Requirement for IV alimentation
• Prior surgical procedures affecting absorption
• Uncontrolled inflammatory GI disease (e.g., Crohn's disease or ulcerative colitis)
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 6 months after completion of study treatment

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• No prior chemotherapy, radiation therapy, immunotherapy, or biotherapy for breast cancer
• No primary breast radiation therapy as part