Breast cancer is the most common cause of cancer-related death in women. Breast cancer requires medical treatments at varying costs based on the stage and treatment given. Expensive medical treatment, however, does not necessarily affect the patients’ quality of life. Therefore, it is necessary to calculate the cost-effectiveness of the treatment based on the value of quality of life (QALY) of breast cancer patients who have undergone treatment. To determine the total cost incurred for the breast cancer patients at early-stage, locally advanced stage, and advanced stage and to analyze the cost-effectiveness of treatment at each stage based on the quality of life (QALY). Observational analysis of breast cancer patients who underwent examination and treatment at the Surgical Oncology Clinic of Saiful Anwar Regional Public Hospital, Malang. Respondents were divided into 3 study groups based on the stage when the patient first underwent the examination. From each respondent, the total costs incurred by the hospital for the patient were calculated, and each respondent filled out the EQ-5D questionnaire to determine the U-QALY value (converted using the EQ-5D Thailand conversion table). The effectiveness evaluation was done by calculating the Incremental Cost Effectiveness Ratio (ICER) and based on the Threshold (the value of Indonesia's per capita income). Of the total 87 respondents in this study, 10% were early-stage patients, 65% locally advanced stage, and 25% advanced stage. The average U-QALY scores for each group were 0.92, 0.85, and 0.6 consecutively. Cost-effectiveness in the early stage group was categorized to be positive because it did not show an increase in QALY. In the locally advanced stage group, the ICER value in the mastectomy and chemotherapy group was Rp. 24,000,000.00 / 0.3 QALY gained and Rp. 39,000,000.00 / 0.5 QALY gained in the mastectomy, chemotherapy, and radiotherapy groups. In the advanced stage group, the ICER value was Rp. 15,000,000.00 / 0.5 QALY gained in the radiotherapy group. The quality of life of breast cancer patients (measured in QALY value) was strongly influenced by the stage of the disease. The higher the stage, the lower the QALY value. The Cost-Effectiveness in the early stage, locally advanced stage, and advanced stage at Saiful Anwar Hospital was relatively positive because its value was lower than the threshold value.