Breast Cancer Patient Protection Act of 2003 - Amends the Public Health Service Act and the Employee Retirement Income Security Act of 1974 (ERISA) to prohibit group health plans and health insurance issuers offering group health insurance coverage, with regard to hospital stays in connection with breast cancer treatment, from: (1) covering less than 48 hours after mastectomies or less than 24 hours after lymph node dissections; or (2) requiring plan or issuer authorization for prescribing any length of stay. Prohibits: (1) denying eligibility, enrollment, or renewal to avoid these requirements; (2) providing payments or rebates to women; or (3) penalizing or providing incentives to providers. Applies the same requirements to issuers in the individual market.