Hormone therapy in the treatment of breast cancer

Currently, hormone therapy is a widely used method in the treatment of hormone receptor-positive breast cancer. These therapies include the use of certain drugs that block or inhibit estrogen from having a negative effect on breast cancer cells, thereby preventing the cancer from progressing or coming back.

Hormone therapy is often used after surgery, as an adjuvant therapy to help reduce the risk of cancer recurrence. Sometimes, it can also be applied before surgery begins. Typically, hormone therapy will be done for at least 5 to 10 years.
In addition, hormone therapy can also be used to treat cancer that has come back after treatment or has spread to other parts of the body.

Out of 3 breast cancer patients, about 2 are hormone receptor positive. The cells in their body will have receptors (proteins) corresponding to the hormones estrogen (ER-positive breast cancer) or progesterone (PR-positive cancer) that cause cancer cells to grow and spread spread quickly.
Currently, a number of hormone therapies for breast cancer have been widely applied. Most types of hormone therapy have the ability to lower estrogen levels or block the hormone from negatively affecting breast cancer cells.

These drugs will work by blocking estrogen from promoting breast cancer cells to grow.
3.1.Tamoxifen This is a drug that can block estrogen receptors on breast cancer cells. It works by preventing estrogen from connecting with cancer cells, thereby inhibiting their growth and division. Tamoxifen not only acts as an anti-estrogen in breast cells, but also acts as an estrogen in other tissues, such as in the uterus and bones. Therefore, it is also known as selective estrogen receptor modulator (SERM), which is commonly used to treat women who have had breast cancer or have not yet gone through menopause.
Tamoxifen may be used in the following specific situations:
Tamoxifen works to reduce the risk of developing breast cancer in women who are at high risk for this cancer. For women who have been treated with breast-conserving surgery for hormone receptor-positive ductal carcinoma in situ (DCIS) receiving tamoxifen for 5 years to reduce the likelihood of DCIS relapse. In addition, this drug also significantly reduces the risk of invasive breast cancer in both breasts.

For women with hormone receptor-positive invasive breast cancer who have been treated with surgery, tamoxifen can be used to reduce the risk of cancer recurrence and increase the chance to live longer. In addition, this drug also helps reduce the risk of new cancer in the other breast. Tamoxifen can be used after surgery (adjuvant therapy) or before surgery (neo-adjuvant), and is usually given for 5-10 years. This drug is mainly for women who have early stage breast cancer and have not gone through menopause. If you've been through menopause, aromatase inhibitors are often used instead. For women whose hormone receptor-positive breast cancer has spread to other parts of the body, tamoxifen can help slow or stop the growth of cancer, and even shrink some tumors. Besides tamoxifen, toremifene (Fareston) is another SERM that works in a similar way, but is less commonly used and is only approved for the treatment of metastatic breast cancer in postmenopausal women. . Furthermore, this medicine will not work if tamoxifen has been used before and has stopped working. Most toremifene medicines come in pill form and are taken by mouth.
However, using tamoxifen and toremifene can cause certain side effects, including:
Hot flashes Vaginal dryness or discharge Some women have cancer that has spread to the bones There may be a tumor outbreak accompanied by bone pain. Although the condition can be relieved quickly, in rare cases, a patient's blood calcium level can become elevated and difficult to control. When that happens, treatment may need to be stopped for a while.
Some other rare but more serious side effects can also occur, including:
SERMs may increase the risk of developing uterine cancer if a patient has gone through menopause. Blood clots are an uncommon, but very serious side effect to health. They usually form in the legs (deep vein thrombosis or DVT), but can sometimes rupture and block an artery in the lung (pulmonary embolism or PE). Rarely, tamoxifen has been associated with stroke in postmenopausal women, however if there are signs of severe headache, confusion or difficulty speaking or moving; seek medical help immediately.

In addition, tamoxifen can have different effects on bones depending on each woman's menopausal status. In premenopausal women, tamoxifen is more likely to cause osteoporosis, while in postmenopausal women, they often help strengthen bones. Overall, the benefits these drugs offer to most women with hormone receptor-positive breast cancer outweigh the risks. Therefore, this is still an effective treatment for breast cancer patients.
3.2.Fulvestrant (Faslodex) Fulvestrant is a drug that blocks and damages estrogen receptors. This drug is not a SERM and it acts like an anti-estrogen throughout the body. In addition, they are known as a selective estrogen receptor degrader (SERD). Fulvestrant is currently only approved for use in postmenopausal women. It is also sometimes used off-label in premenopausal women and is often combined with a luteal-releasing hormone (LHRH) agonist to remove the ovaries.
In general, fulvestrant is usually used in the following situations:
Used exclusively to treat advanced breast cancer that has not been treated with other hormone therapy. Used exclusively to treat advanced breast cancer after other hormonal drugs such as tamoxifen have worn off. Use in combination with a CDK 4/6 inhibitor or a PI3K inhibitor to treat metastatic breast cancer as initial hormone therapy or after other hormone treatments have been tried. This drug is usually injected into the buttocks. For the first month, the injections will be spaced 2 weeks apart, then given once a month. In addition, fulvestrant can also cause some short-term side effects, such as:
Hot flashes and night sweats Headaches Mild nausea Bone pain Pain at the injection site

Some hormone treatments work by lowering the level of estrogen in the patient's body. Because estrogen is a growth promoter of hormone receptor-positive breast cancer, reducing estrogen levels can help slow the cancer's progression or prevent it from coming back.
4.1.Aromatase Inhibitors (AI) Aromatase Inhibitors (AI) are drugs that help the body stop producing estrogen. Before menopause, most estrogen will be made by the ovaries. However, in women whose ovaries are inactive due to menopause or some treatment, small amounts of estrogen are still produced in fatty tissues by the enzyme aromatase. So when using AI, they can block aromatase from producing estrogen.
These drugs are especially helpful in women who have gone through menopause. Some of the most commonly used oral AI tablets in breast cancer treatment include:
Letrozole (Femara) Anastrozole (Arimidex) Exemestane (Aromasin) *Use of AI in adjuvant therapy: after surgery , hormone therapy can be done to reduce the risk of cancer recurrence. At that time, patients can use AI alone, or use it after tamoxifen to increase the effectiveness of treatment.
Several effective AI therapy schedules include:
Take tamoxifen for 2-3 years, followed by AI to complete treatment for 5-10 years Use AI for 2-3 years, followed by tamoxifen to complete 5 years of treatment Take tamoxifen for 5 years, followed by AI for 5 years Only use AI for 5-10 years If you have early breast cancer and have not gone through menopause, you should take tamoxifen first, then AI. Another drug is a luteinizing hormone-releasing hormone (LHRH) analog, which removes the ovaries when used with AI. In addition, it should be noted that AI alone should not be used to treat breast cancer in premenopausal women because it is unsafe and may increase hormone levels.
*Using AI for recurrent or metastatic cancer: AI can also be used to treat more advanced hormone-positive breast cancers, especially in postmenopausal women.

*Side effects that occur with AI: the side effects of AI are usually less severe than with tamoxifen. They do not cause uterine cancer and very rarely cause blood clots. However, they can cause muscle pain, stiffness, or joint pain. Joint pain can feel like arthritis in many different joints at the same time. Switching to a different AI drug can improve this side effect, but in some cases treatment is likely to have to be stopped. If this happens, most doctors recommend using tamoxifen to complete 5 to 10 years of hormone therapy.
Because AIs drastically reduce estrogen levels in postmenopausal women, they can cause osteoporosis and even fractures. If you're using AI, check your bone density and consider adding some other medications, like bisphosphonates (zoledronic acid) or denosumab (Xgeva, Prolia) to promote bone health.
4.2. Ovarian suppression Here are a few methods to help remove or suppress the ovaries (where estrogen is produced) to treat breast cancer:
Ovectomy : surgical removal of the ovaries permanently Analogs luteinizing hormone-releasing hormone (LHRH): these drugs are more commonly used than oophorectomy. They help block the signals the body sends to the ovaries to make estrogen and cause temporary menopause. Common LHRH drugs include goserelin (Zoladex) and leuprolide (Lupron). They may be used alone or together with certain other hormone medications (tamoxifen, aromatase inhibitors, fulvestrant) as hormone therapy in premenopausal women. Chemotherapy drugs: Some chemotherapy drugs can damage the ovaries in premenopausal women and make them unable to produce estrogen anymore. However, ovarian function can recover after several months or years. There are also some cases of permanent ovarian damage that leads to menopause. All of these methods can cause menopausal symptoms, including hot flashes, night sweats, vaginal dryness, and mood swings.

Some less commonly used hormone therapies, such as:
Megestrol acetate (Megace), a progesterone-like medicine Androgen (male hormone) High-dose Estrogen These may be other treatment options if the Previous hormone therapies are no longer effective, but they often cause side effects.
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References: cancer.org