Anti-estrogen drugs are used to treat hormonally responsive cancers, such as breast or ovarian cancer. Cancer cells in hormonally responsive tumors detect the presence of estrogen in the bloodstream and respond to the estrogen by proliferating. As a result, estrogen is a driving force in some types of cancer progression. Anti-estrogen drugs work either by preventing the synthesis of estrogen in the body or by preventing the cells from responding to existing estrogen. These drugs typically lead to a number of side effects due to the disruption of normal estrogen signaling.
Hot Flashes
Hot flashes are a common side effect of anti-estrogen therapy, with many of the major anti-estrogen drugs listing it as a side effect, according to BreastCancer.org. Hot flashes develop during hormonal therapy because the inhibition of estrogen signaling modifies the function of the hypothalamus, an important region of the brain. Under normal conditions, the hypothalamus acts as a control center for the body, helping to regulate body temperature, appetite and sleeping patterns. Cells within the hypothalamus normally sense the presence of estrogen, and hormone levels in the body help the hypothalamus regulate body functioning. During anti-estrogen therapy, disruptions in hormone levels in the body can disrupt the hypothalamus, leading to sudden hot flashes. This side effect of anti-estrogen treatment is temporary, and will abate after treatment is completed.
Osteoporosis
Another possible side effect of long-term anti-estrogen therapy is the development of osteoporosis. Patients with osteoporosis develop a progressive loss of bone density. Hydroxyapatite, the calcium-containing mineral that causes the hardness of bone tissue, gradually breaks down, leading to bone weakness and an increased risk of injury. Normally, estrogen in the body prevents calcium from leaking out of bone tissue, and therefore helps keep the bone strong, according to Dr. Gabe Mirkin of DrMirkin.com. Patients receiving anti-estrogen treatment should monitor their bone density during treatment to detect a risk for developing osteoporosis.
Pain
Another common symptom of anti-estrogen treatment is pain. The chronic bone wasting that can accompany treatment can lead to bone and joint pain, and many anti-estrogen drugs list joint pain as a side effect, according to BreastCancer.org. Patients taking anti-estrogen therapies may also experience pain since natural estrogen levels help women modulate and regulate pain. A study published in the journal "Pain" in 2007 indicates that estrogen plays a role in relieving pain from a range of conditions. As a result, the chronic low levels of estrogen signaling in patients taking anti-estrogen therapy may leave the patient more vulnerable to pain. Although the exact mechanism by which estrogen helps regulate pain remains unknown, the role of estrogen in pain management should be considered in patients taking anti-estrogen therapy.
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