Topical Dermaprazole for Radiation Dermatitis in Breast Cancer Patients (TOPAZ)

Inclusion Criteria:

1. Women with breast cancer, treated with ipsilateral i) Simple (total) mastectomy, OR ii) Modified radical mastectomy, OR iii)Radical mastectomy, OR iv) Segmental mastectomy, OR v) Skin sparing/nipple sparing mastectomy
2. Histological diagnosis of invasive ductal or lobular carcinoma (diagnosed within 2 years of enrollment)
3. Planned to receive adjuvant chest wall radiation of at least 40Gy or higher biologically equivalent dose (BED)
4. Age 18 years or older
5. Women of childbearing potential (any woman with menses in the last 12 months) must agree to pregnancy testing and contraceptive use throughout the study period. Testing consists of human chorionic gonadotropin (HCG) urine testing, which if suspected to be falsely positive may be confirmed by ultrasound. If ultrasound is negative, patient is considered not pregnant and eligible for inclusion in the study. In addition to routine contraception method such as barrier devices, hormonal methods, and intrauterine devices, heterosexual celibacy, and surgical sterility (hysterectomy, bilateral oophorectomy, bilateral tubal ligation, or a partner with history of vasectomy) is considered acceptable. If a celibate patient chooses to become sexually active during the study period, she must use one of the listed methods of contraception throughout the study period.
6. Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2
7. Written Informed Consent
8. History and Physical within 12 weeks of enrollment

Exclusion Criteria:

1. Prior chest wall radiotherapy
2. Any serious medical condition or illness that would preclude the safe administration of the study drug including, but not limited to: active infection, symptomatic heart failure, unstable angina, psychiatric illness or social situations that would limit compliance with treatment
3. Concurrent chemotherapy
4. Biopsy-proven epidermal involvement or positive margins
5. Open wound at time of consultation, or delayed surgical wound healing as defined as open wound \>8 weeks post-op
6. Known active collagen vascular disease such as systemic lupus erythematous, scleroderma or dermatomyositis.
7. Allergy or sensitivity to proton pump inhibitors
8. Pregnancy or breast feeding
9. Use of clopidrogrel, St. Johns Wort, rifampin, or methotrexate