Aromatase inhibitors are drugs that can lower the level of estrogen in the body by inhibiting the action of the enzyme aromatase. Aromatase is required for the biosynthesis of the hormone estrogen. It helps the adrenal glands convert androgen into estrogen, and thereby, increase the level of estrogen in the body. Aromatase inhibitors are mainly used for treating breast cancer in post-menopausal women.
These medications are however not very effective in reducing the level of estrogen in premenopausal women, as before menopause, the synthesis of estrogen is mainly carried out by the ovaries. Therefore, these medications are not used to treat breast and ovarian cancer in premenopausal women. Aromatase inhibitors are generally classified into two categories – irreversible steroidal inhibitors and non-steroidal inhibitors.
Aromatase Inhibitors for Breast Cancer Treatment
These medications can control the growth of malignant or cancerous cells in the breast by inhibiting the conversion of androgen into estrogen. Certain cells of the breast tissues contain estrogen receptors. Estrogen binds with these receptors to stimulate the growth of breast tissues. But in breast cancer, when estrogen binds with these receptors, it can contribute towards the rapid growth of the cancerous cells in postmenopausal women. Therefore, it becomes imperative to control the level of estrogen in the body, in order to prevent the proliferation of the cancerous cells.
In postmenopausal women, the ovaries stop producing estrogen, but the hormone androgen is converted to estrogen by the adrenal glands with the help of the enzyme aromatase. Aromatase inhibitors can inhibit the actions of the enzyme aromatase, and prevent the synthesis of estrogen. They are generally recommended after the initial cancer treatment like surgery, chemotherapy, and radiation therapy. Sometimes, they are also used for treating breast cancer in the early stage. But they are usually prescribed to patients who have used tamoxifen for 2 to 3 years. Tamoxifen is the drug that is commonly used for treating breast cancer. It has been observed that the possibility of recurrences of breast cancer in postmenopausal women reduces significantly, if these medications are taken for 5 years after taking tamoxifen for about 5 years.
Aromatase Inhibitors Dangers
There are mainly three types of aromatase inhibitors that are used for the treatment of breast cancer in postmenopausal women. They are known as anastrozole, Aromasin or exemestane, and Femara or letrozole. The side effects of these medications are usually mild. As compared to the side effects of tamoxifen, serious side effects of aromatase inhibitors are not very common. One of the most common side effects of these medications is bone loss or osteoporosis, which can develop gradually over a period of time. An increased risk of osteoporosis can increase the chances of having bone fractures.
Apart from these, some other common side effects of these medications are, increase in joint pain or stiffness, and hypercholesterolemia. Joint pain and stiffness have been found to affect about 50% women taking these medications. Hypercholesterolemia on the other hand, is a condition characterized by the presence of excess cholesterol in the cells and blood plasma. This condition is caused by a reduction in the level of estrogen in the body. This condition can raise the risk of atherosclerosis, where the arteries become narrow due to the deposition of fats inside the arterial wall. This in turn, may increase the risk of developing heart or cardiovascular diseases. In addition to these, some women can experience hot flashes, headaches, muscle aches, and vaginal dryness after using these drugs.
Considering the side effects of these medications, cancer patients using these drugs should consult a physician to monitor their health condition at regular intervals. The main side effect caused by these drugs is bone thinning or osteoporosis. So, women taking these drugs should check their bone mineral density at regular intervals. Sometimes, physicians can recommend bone strengthening drugs to counteract this side effect. However, the bone thinning induced by these medications usually stop when their use is discontinued. But still, any kind of side effects experienced while using these drugs should be reported to a physician to avoid any complications.