Women's Health

Estrogen Modulator for Breast Cancer

Estrogen Modulator for Breast Cancer

Hormone Receptor Breast Cancer

There are certain types of breast cancer that are mostly affected by the hormones that are produced by the body. They are known as ER positive and PR positive breast cancer cells. These cells have receptors that are attached to the estrogen in the body. This estrogen hormone helps these cells to grow and multiply. There are various ways to stop the estrogen from getting attached to these cell receptors. One of the forms of systemic therapy is known as hormone therapy. In this therapy, it reaches out to the cancer causing cells that can be present anywhere in the body and not just limited to the breast. This hormone based therapy is often used once the surgery is carried out or adjuvant therapy is done so as to help to reduce the risk of recurrence of cancer. In some cases, this hormone therapy is started prior to conducting the surgery. It is mostly used for a period of five years.

To determine if the breast cancer is due to hormone receptors, the doctors would need to conduct certain lab tests of the tumor tissue that was removed during the surgery procedure. If the tumor cell contains estrogen, then the cancer is called estrogen receptor positive, and if it contains progesterone receptors, then the cancer is called progesterone receptor positive. The majority of the hormone based breast cancers are ER based. In some cases, if the breast tumor contains both the hormones, then it is called hormone receptor positive.

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About two out of three cases of breast cancer would be reported as hormone receptor positive. For such type of cancer, high levels of estrogen in the body act as a medium for growth and development of the cancer cells. Hence, most of the hormone based therapies aim to reduce the estrogen levels or completely stop the production of estrogen levels from acting on these breast cancer cells.

Estrogen Modulator

Estrogen Modulators, also known as Selective Estrogen Receptor Modulators (SERMs), help in treating the symptoms by blocking the effects of estrogen on the tissues of the breast. SERMs work by sitting in the estrogen receptors that are present in the breast cells. By doing so, they do not leave any room for estrogen in the estrogen receptor, and thus it would not be able to attach any cells to it. If the estrogen is not attached to a breast cell, then the cell does not receive any signals of estrogen for growth and multiplication.

There are cells that are also present in other tissues in the body, such as those in the uterus and bones. These also have estrogen receptors, but each of the estrogen receptors has a different structure that would depend on the kind of cell. In other words, one can say that a breast cell estrogen receptor would be different than the bone cell estrogen receptor, and both of these would be different from the uterus or uterine estrogen receptor. SERM, as the name says “Selective,” means that it helps to block the actions of the estrogen present in the breast cells; however, it can also lead to activating the actions of the estrogen present in the other cell tissues, such as the bones, uterus, or liver.


Since Tamoxifen is the widely used drug, most of the studies revolve around comparison between SERMs and aromatase inhibitors. This has been done to identify which type of medicine is more effective in treating the early stages, as well as the hormone receptor breast cancer in postmenopausal women, and based on the results of the comparison, the following recommendations were made from the study:

  • When it comes to the aromatase inhibitor, it is the best form of hormonal therapy to be started for post-menopausal women, since there have been more benefits seen and fewer risks of any side effects as compared to tamoxifen.
  • After taking tamoxifen for a period of two to three years, switching to aromatase inhibitor offers a lot of benefits, rather than using tamoxifen for a period of five years at a stretch. Taking aromatase for a period of five years after the treatment of tamoxifen for a period of five years helps to reduce the risk of recurrence of cancer when compared to no treatment after five years of tamoxifen.

Three Common Brands of SERMs:

Tamoxifen is known to be the oldest and also the most used treatment in cases of breast cancer. The doctor can prescribe SERM for women suffering from breast cancer, both prior to and after the menopause stage.

Tamoxifen: Tamoxifen is used as a treatment plan in certain types of breast cancer that require estrogen to grow. Tamoxifen causes the blockage of the actions of estrogen, which is a female hormone. This medicine is also used in some cases in which it is necessary to lower the woman’s chance of developing breast cancer if she has a family history of breast cancer. Then she would also be at a higher risk of developing the same. You should not take Tamoxifen if you are pregnant or planning for a pregnancy, or if you are nursing a baby, since it could lead to harming the growth of the baby. Also, do not use Tamoxifen if you are allergic to any kind of food, medicine, or any substances and contents present in Tamoxifen. Those individuals who have a medical history of clotting of the blood, or if they are already on blood thinning medicine, such as warfarin, should not use Tamoxifen. Before you start to take this medicine, inform the doctor if you are suffering from any kind of liver related disorder, have a history of cataracts, or if the body is high in triglycerides, which is a certain type of fat in the blood, if there is a history of stroke or any heart related disorder. Also, let the doctor know if you are currently on chemotherapy or radiation therapy.

Usually, once you start the first dose of Tamoxifen, it has to be taken when you are having a menstrual period. Intake of Tamoxifen can lead to cancer related to lung, clotting of the blood in the lungs, which could turn out to be fatal. Tamoxifen should be taken exactly as prescribed by the doctor, and you can also check the label of the medicine for the detailed information on dosing and usage. Avoid increasing or decreasing the dosage of this medicine without the recommendation from the doctor, or else it can lead to serious side effects. If you are taking the liquid form of Tamoxifen, then measure the liquid with the dosing syringe that has been provided. Tamoxifen can be taken with or without food. During the treatment of Tamoxifen, you would be asked to carry out blood tests. The doctor would also conduct regular physical exams and also mammograms. Self-examination of the breasts for any signs of formation of lumps needs to be done on a monthly basis. In certain cases, an individual would be asked to continue this medicine for a period of five years.

The adult dosage for breast cancer is 20 to 40 mg to be taken orally and divided throughout the day, which means during the morning and evening. So as to reduce the risk of breast cancer in women having a family history of breast cancer, those women would be given 20 mg to be taken orally daily for a period of five years. For the treatment of breast cancer in postmenopausal women, the dosage would be 10 mg to be taken orally two to three times per day for a period of five years.

The common side effects of Tamoxifen are hot flashes, sudden weight loss, and unusual vaginal discharge. The severe cases of side effects are changes in the menstrual period, blurry vision, new lumps in the breast, pressure or pain in the pelvis region, vaginal bleeding or discharge that is unusual, hallucinations, problems pertaining to the liver, such as itching, feeling tired, loss of appetite, and jaundice signs. High levels of calcium in the blood with symptoms such as nausea, constipation, feeling tired, frequent urge for urination or feeling thirsty, weakness in the muscles, and vomiting. Signs of a stroke with symptoms such as slurred speech, severe forms of headache, sudden weakness, and tingling feeling may occur. Signs of clotting of the blood in the lungs, such as pain in the chest, wheezing, fast breathing, and bloody coughing are severe side effects.

Exemestane (Aromasin): Exemestane is a drug that is used for treating advanced stages of breast cancer in women who are in their post-menopausal stage wherein the cancer has progressed even after carrying out other forms of treatment. It can also be used in the treatment of the early stages of breast cancer in certain women, particularly those past menopause and after carrying out treatment with other forms of medicines. Exemestane falls under the category of aromatase inhibitor, and it works by stopping the production of estrogen, which in turn can lead to a decrease in the size as well as the growth of the tumor. Do not use Exemestane if you allergic to any food, medicine, or content of Exemestane or any other substances, if you are planning of pregnancy or are pregnant, if you are nursing a baby, if you are currently on any medication that has traces of estrogen, such as birth control pills, hormone replacement therapies, etc., or if you have not yet undergone menopause. Before starting the treatment with Exemestane, inform the doctor if you are taking any medicines or drugs, vitamins or minerals, whether prescribed or non-prescribed, if you have a medical history or are currently suffering from a kidney related disorder, weakening of the bones or osteoporosis, heart related problems, and problems pertaining to the blood vessels. There can be certain medications that could interact with Exemestane, and the same should be informed to the doctor, or else it would increase the risk of side effects. Medicines that contain estrogen such as birth control pills or rifampin, carbamazepine or St John’s Wort can lead to a decrease in the effectiveness of Exemestane if taken together. Exemestane should be taken as directed by the doctor, or you can check the label of the medicine for the dosing instructions, as well as the correct usage. Exemestane should be taken orally after a meal. This medicine should be taken daily at the same time to increase its effectiveness against the disease. Exemestane can lead to signs of dizziness, and this can tend to worsen if you consume alcohol or smoke. Hence, use Exemestane with caution, and do not carry out any tasks that would require mental alertness. It may take several weeks for the symptoms to start showing the signs of improvement. Also, do not take this medicine for a long duration without the confirmation from the doctor. The common side effects pertaining to Exemestane are pain in the joints and limbs, diarrhea, dizziness, hair loss, headache, anxiety attacks, mental changes or mood swings, excessive sweating, coughing, having trouble while sleeping, pain in the stomach or stomach upset, symptoms related to the flu, hot flashes, and nausea.

The doctor will regularly monitor the conditions while you are on the Exemestane treatment. This would be done to monitor the side effects and also find the response to the treatment. The doctor would also check for the levels of Vitamin D and carry out a bone density test before the start of this treatment. Also, during the duration of the treatment, these checks would be carried out on a timely basis.

Side Effects

One cannot overlook the side effects that can be caused by SERM medications, which would include clotting of the blood, stroke, or endometrial cancer. If the doctor is considering prescribing tamoxifen or any other SERM, then the doctor should know about your past history of heart stroke or blood clotting. The common side effects of SERM are fatigue, mental changes, or mood swings, hot flashes, sweating in the night, and unusual vaginal discharge. The severe forms of side effects of SERM are pain in the chest, shortness of breath, vaginal bleeding that is abnormal, vision issues or blurry vision, feeling weak, swelling and tenderness in the legs, dizziness, numbness in the face, legs, or arms, and pain or pressure in the pelvic region. For any of these side effects, one should inform the doctor immediately. The common side effects would usually go away in a couple of days; however, if they worsen, then do not overlook them, and inform the doctor.