Reasons for Changing HOrmonal Therapy of Advanced Breast Cancer (HOT ABC)

Breast cancer is the leading type of cancer in women. Although big advance in diagnostics and treatment of early and breast cancer has been made in recent years breast cancer still has a significant mortality rate. A number of treatment modalities exist for postmenopausal women with advanced breast cancer. The treatment modality is chosen based on patient and tumour characteristics. Hormonal treatment is preferred and recommended in women with hormone sensitive breast cancer (ESMO, CECOG and NCCN guidelines). Tumor markers are an established method of monitoring systemic therapies in various cancers. Tumor markers CA 15-3 and CEA are used in clinical practice to monitor treatment efficacy of metastatic breast cancer. Blood levels of tumor markers are widely used to assess response/progression to treatment and guide therapy change. Treatment efficacy is assessed by imaging methods in clinical studies. Change of therapy in clinical study is usually done when progression based on RECIST criteria is found. Hormonal treatment has slower onset of effect compared with chemotherapy that can last several weeks. Also when a new therapy is started spurious early rises may occur. Therefore rising levels of tumor markers during the first weeks of new hormonal therapy are not necessarily sign of progression and should not be the only guidance for treatment change. Evidence of treatment efficacy form clinical studies and treatment change is based on imaging techniques.