This randomized phase I/II trial studies the side effects and best dose of lapatinib ditosylate and to see how well it works in treating patients with ductal breast carcinoma in situ. Lapatinib ditosylate may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.

PRIMARY OBJECTIVES:

I. Determine whether lapatinib (lapatinib ditosylate) therapy at the dose of 1000 mg results in a statistically significantly lower rate of proliferation in ductal carcinoma in situ (DCIS) breast cancer cells as measured by Ki67 when compared to placebo.

II. Determine the toxicity profile and frequency of adverse events in women with DCIS breast cancer taking lapatinib at 1000 mg as compared to women taking placebo.

SECONDARY OBJECTIVES:

I. Determine whether lapatinib treatment affects the incidence of DCIS seen at the time of surgical excision.

II. Determine whether treatment with lapatinib will modulate breast tissue histology or the expression of specific biomarkers in normal and DCIS breast cancer cells.

OUTLINE: Patients are randomized to 1 of 2 treatment arms.

ARM I: Patients receive lapatinib ditosylate orally (PO) once daily (QD) for 2-6 weeks until the time of surgery.

ARM II: Patients receive placebo PO QD for 2-6 weeks until the time of surgery.

After completion of study treatment, patients are followed for 4-5 weeks.

Inclusion Criteria:

• Participants must be premenopausal or postmenopausal
• Participants must have a diagnosis of ductal carcinoma in situ made by core needle biopsy
• The DCIS cells must have high expression of human epidermal growth factor receptor 2 (erbB2) (3+ by immunohistochemical staining or amplification by fluorescence in situ hybridization [FISH]), and/or have detectable expression of epidermal growth factor receptor (EGFR) (1+ or more by immunohistochemical staining)
• All participants must be informed of the investigational nature of this study and must sign and give written informed consent in accordance with institutional and federal guidelines
• Individuals with a diagnosis of breast cancer, non-melanoma skin cancer, cervical cancer in situ, or early bladder cancer are eligible if they have not been treated with chemotherapy, biological therapy, or breast radiotherapy to the breast currently affected by DCIS within one year; in addition, individuals with a diagnosis of breast cancer may not have used tamoxifen, raloxifene, or other antiestrogen compounds within three months of study day 1
• If subjects are of reproductive potential, they must agree to use a reliable contraceptive method or be sexually abstinent; subjects must fulfill these conditions beginning at the time of starting study medications and ending one month after study termination
• Negative serum pregnancy test (beta-human chorionic gonadotropin [HCG]) at baseline (within 30 days of day 0) for women of child bearing potential
• Serum creatinine =< 1.5 times the institution?s upper limit of normal
• Total bilirubin =< 1.5 times the institution's upper limits of normal
• Serum glutamic oxaloacetic transaminase (SGOT) =< 1.5 times the institution's upper limits of normal
• Alkaline phosphatase =< 1.5 times the institution's upper limits of normal
• Albumin =< 1.5 times the institution's upper limits of normal
• White blood cells (WBC) > 4.0 k/uL
• Platelet count > 100,000/uL
• Hematocrit of > 30%
• Cardiac ejection fraction within normal limits for the institution by multi gated acquisition scan (MUGA) scan or normal cardiac ultrasound (defined as within the upper limit of normal [ULN] for the institution)
• Eastern Cooperative Oncology Group (ECOG) performance status =< 2
• Willingness to refrain from donating blood to others during the study

Exclusion Criteria:

• Individuals are ineligible if they have either active cancer or a prior history of malignancies other than (e.g., breast cancer, skin cancer [basal or squamous cell carcinoma], cervical cancer in situ, or early bladder cancer [preinvasive transitional cell carcinoma of the bladder]) within the past five years
• Participants are ineligible if they are currently being treated with tamoxifen, raloxifene, or with aromatase inhibitors (letrozole, anastrozole, exemestane)
• Individuals are ineligible if they have received chemotherapy, biological therapy (e.g., Herceptin), or radiotherapy for the treatment of any cancer within 1 year or if they have received tamoxifen, raloxifene, letrozole, anastrozole, or exemestane therapy within 3 months of study day 1
• Individuals currently receiving anticoagulation therapy (e.g., Coumadin) are ineligible
• Blood urea nitrogen [BUN] > 1.5 x ULN or
• Creatinine [Cr] > 1.5 x ULN
• SGOT > 1.5 x ULN
• Serum glutamate pyruvate transaminase (SGPT) > 1.5 x ULN
• Alkaline phosphatase > 1.5 x ULN
• Bilirubin > 1.5x ULN
• Individuals who are currently participating in a study of an investigational drug
• Pregnancy, lactation or unwillingness to use a reliable contraceptive method in women of childbearing potential
• Severe underlying chronic illness or disease, such as uncontrolled diabetes
• Individuals with known congestive heart disease or previous myocardial infarction are ineligible
• Patients taking any prohibited medications
• Individuals with hypokalemia or hypomagnesemia are ineligible unless these conditions are corrected to within normal limits before starting drug
• Individuals with congenital long QT syndrome or baseline QTcF intervals > 480 msec on electrocardiogram (EKG)
• Individuals taking anti-arrhythmics, beta blockers, or other medications that may lead to QT prolongation
• Individuals who have received a cumulative dose of anthracycline therapy greater than 500 mg/m^2 are ineligible

Subjects followed up to 4-5 weeks after surgery to assess for adverse events with overall collection period approximately five years, first study period January 2008 to March 2010 and second September 2011 to August 2014.