Treating breast cancer under the constraints of significantly limited health care resources poses unique challenges that are not well addressed by existing guidelines. We present evidence-based guidelines for systematically prioritizing cancer therapies across the entire spectrum of resource levels. After consideration of factors affecting the value of a given breast cancer therapy (contribution to overall survival, disease-free survival, quality of life, and cost), we assigned each therapy to one of four incremental levels--basic, limited, enhanced, or maximal--that together map out a sequential and flexible approach for planning, establishing, and expanding breast cancer treatment services. For stage I disease, basic-level therapies are modified radical mastectomy and endocrine therapy with ovarian ablation or tamoxifen; therapies added at the limited level are breast-conserving therapy, radiation therapy, and standard-efficacy chemotherapy (cyclophosphamide, methotrexate, and 5-fluorouracil [CMF], or doxorubicin and cyclophosphamide [AC], epirubicin and cyclophosphamide [EC], or 5-fluorouracil, doxorubicin, and cyclophosphamide [FAC]); at the enhanced level, taxane chemotherapy and endocrine therapy with aromatase inhibitors or luteinizing hormone-releasing hormone (LH-RH) agonists; and at the maximal level, reconstructive surgery, dose-dense chemotherapy, and growth factors. For stage II disease, the therapy allocation is the same, with the exception that standard-efficacy chemotherapy is a basic-level therapy. For locally advanced breast cancer, basic-level therapies are modified radical mastectomy, neoadjuvant chemotherapy (CMF, AC, or FAC), and endocrine therapy with ovarian ablation or tamoxifen; the therapy added at the limited level is postmastectomy radiation therapy; at the enhanced level, breast-conserving therapy, breast-conserving whole-breast radiation therapy, taxane chemotherapy, and endocrine therapy with aromatase inhibitors or LH-RH agonists; and at the maximal level, reconstructive surgery and dose-dense chemotherapy and growth factors. For metastatic or recurrent disease, basic-level therapies are total mastectomy for ipsilateral in-breast recurrence, endocrine therapy with ovarian ablation or tamoxifen, and analgesics; therapies added at the limited level are radiation therapy and CMF or anthracycline chemotherapy; at the enhanced level, chemotherapy with taxanes, capecitabine, or trastuzumab, endocrine therapy with aromatase inhibitors, and bisphosphonates; and at the maximal level, chemotherapy with vinorelbine, gemcitabine, or carboplatin, growth factors, and endocrine therapy with fulvestrant. Compared with the treatment of early breast cancer, the treatment of advanced breast cancer is more resource intensive and generally has poorer outcomes, highlighting the potential benefit of earlier detection and diagnosis, both in terms of conserving scarce resources and in terms of reducing morbidity and mortality. Use of the scheme outlined here should help ministers of health, policymakers, administrators, and institutions in limited-resource settings plan, establish, and gradually expand breast cancer treatment services for their populations.