Breast cancer is a complex disease characterized by the uncontrolled growth of abnormal cells in the breast tissue. It is one of the most frequently diagnosed cancers among women globally. A significant portion of these cases, about 70-80%, are classified as hormone receptor-positive (HR-positive) breast cancer.
Understanding Hormone Receptor Positive Breast Cancer
Hormone receptor-positive (HR-positive) breast cancer means that the cancer cells have specific proteins called receptors on their surface or inside them. These receptors can bind to hormones like estrogen and progesterone. When estrogen or progesterone attach to these receptors, they signal the cancer cells to grow and divide. This growth mechanism makes these cancers particularly responsive to treatments that interfere with hormone activity.
The two primary types of hormone receptors are estrogen receptors (ER) and progesterone receptors (PR). If cancer cells have estrogen receptors, the cancer is called estrogen receptor-positive (ER+). Similarly, if they have progesterone receptors, it is termed progesterone receptor-positive (PR+). A breast tumor can be positive for either ER, PR, or both.
Identifying the presence of these receptors is an important step in determining the most effective treatment strategy. Tumors that are HR-positive often grow more slowly than HR-negative tumors, and they have more targeted treatment options available. This receptor status is determined through laboratory tests on a tumor tissue sample, obtained during a biopsy or surgery. The most common test is immunohistochemistry (IHC), which identifies a tumor as HR-positive.
Treatment Approaches for HR Positive Breast Cancer
Hormone therapy, also known as endocrine therapy, is a primary treatment for HR-positive breast cancer. This treatment works by either lowering the levels of hormones like estrogen in the body or by blocking these hormones from attaching to the cancer cells’ receptors. By depriving the cancer cells of the hormonal “fuel” they need, hormone therapy helps to slow or stop tumor growth and can also reduce the risk of cancer recurrence.
Selective Estrogen Receptor Modulators (SERMs) like tamoxifen work by binding to estrogen receptors on cancer cells, preventing estrogen from activating them. Tamoxifen is effective for both premenopausal and postmenopausal women with HR-positive breast cancer. It can be taken for 5 to 10 years after surgery to reduce the chance of the cancer returning.
Aromatase inhibitors (AIs), such as anastrozole, letrozole, and exemestane, are another class of hormone therapy drugs. These medications are primarily used in postmenopausal women because they work by blocking the enzyme aromatase, which converts other hormones into estrogen in the body’s tissues. By reducing overall estrogen levels, AIs slow or stop the growth of HR-positive tumors. AIs may offer a greater benefit in preventing recurrence compared to tamoxifen in postmenopausal women.
While hormone therapy is central to treating HR-positive breast cancer, other treatments may also be used. Surgery is often performed to remove the tumor, and radiation therapy may follow to destroy any remaining cancer cells in the breast area. Chemotherapy, which uses drugs to kill cancer cells throughout the body, may be used for higher-risk cases, such as those with larger tumors or lymph node involvement. Targeted therapies, which focus on specific abnormalities within cancer cells, can also be combined with hormone therapy for advanced HR-positive cases, including drugs like CDK4/6 inhibitors.
Living with and Managing HR Positive Breast Cancer
Living with HR-positive breast cancer often involves a long-term commitment to hormone therapy, lasting 5 to 10 years. Adherence to this medication schedule is important for maximizing its effectiveness in reducing recurrence risk. The specific duration and type of therapy are personalized based on individual factors, including menopausal status and other risk assessments.
Hormone therapy can cause various side effects, which are manageable. Common side effects include hot flashes, night sweats, vaginal dryness, joint pain and stiffness, and fatigue. Less common but more serious side effects can include blood clots with tamoxifen and a potential increase in osteoporosis risk with aromatase inhibitors. Healthcare providers can offer strategies and medications to help manage these side effects, improving comfort and treatment adherence.
Regular monitoring and follow-up care are important after initial treatment for HR-positive breast cancer. This involves physical exams, mammograms, and blood tests or other imaging to watch for any signs of recurrence. While HR-positive cancers tend to grow more slowly, they can recur many years after initial treatment, requiring extended follow-up. Factors like tumor size and lymph node involvement at diagnosis can influence the risk of late recurrence.
Lifestyle factors also play a supporting role in overall well-being and in managing recurrence risk. Maintaining a healthy weight, engaging in regular physical activity, and consuming a balanced diet are recommended. For instance, being physically active for at least 150 minutes per week can help reduce the severity of some hormone therapy side effects like weight gain and joint pain. Limiting alcohol intake and avoiding processed foods and excessive sugar may also contribute to better outcomes.