Clinical Research Directory

Inclusion Criteria: Cohort 1 (premenopausal women at diagnosis converted to postmenopausal) 1. Women who were pre- or perimenopausal at diagnosis 2. Luminal breast cancer (defined as estrogen-receptor positive \>/=10%, HER2-negative disease). 3. Treated with tamoxifen for at least 80% of a 5-year period (+/- 6 months from treatment completion). 4. No clinical signs of metastasis after 5 years tamoxifen treatment. 5. cN+ breast cancer at diagnosis indicating the need for extended adjuvant endocrine therapy. 6. Postmenopausal status at study entry defined according to the National Comprehensive Cancer Network Guidelines. Cohort 2 (postmenopausal women at breast cancer diagnosis) 1. Women who were postmenopausal at diagnosis. 2. Luminal breast cancer (defined as estrogen-receptor positive \>/=10%, HER2-negative disease). 3. Treated with AI for at least 80% of a 5-year period (+/- 6 months from treatment completion). 4. No clinical signs of metastasis after 5 years AI treatment. 5. cN+ breast cancer at diagnosis indicating the need for extended adjuvant endocrine therapy. Exclusion Criteria: Cohort 1 1. Prior invasive breast cancer diagnosis. 2. Other invasive malignancy within 5 years before or after breast cancer diagnosis 3. Non-luminal breast cancer (defined as estrogen-receptor \< 10%). 4. Patients who were unable to complete at least 80% of 5-year initial treatment with tamoxifen. 5. Uncertain menopausal status (unable to evaluate menopausal status according to aforementioned definitions). 6. Recurrent or metastatic breast cancer within or after 5-year initial treatment with tamoxifen (DCIS-only is allowed at any time before or after breast cancer diagnosis). 8\) Unable to give informed consent in Swedish. Cohort 2 1. Prior invasive breast cancer diagnosis. 2. Other invasive malignancy within 5 years before or after breast cancer diagnosis; non-Luminal breast cancer (defined as estrogen-receptor \< 10%). 3. Patients who were unable to complete at least 80% of 5-year initial treatment with AI. 4. Recurrent or metastatic breast cancer within or after 5-year initial treatment with AI (DCIS-only is allowed at any time before or after breast cancer diagnosis). 6\) No contraindication for tamoxifen therapy. 7) Unable to give informed consent in Swedish.