Anastrozole

Potential Health Benefits of Anastrozole

• Combats cancer [1-22]
• Increases pregnancy rate [23-32]
• Improves sperm quality [33-41]
• Improves body composition [42-44]

What is Anastrozole?

Anastrozole, also known as Arimidex, is a drug prescribed for the treatment of breast cancer in women who have been through menopause and those with estrogen-receptor-positive breast cancer. This anti-estrogen drug may also be used as a preventive method to reduce the risk of breast cancer in women who have a family history of the disease. Men with breast cancer may also be treated with anastrozole.

How does Anastrozole Work?

Anastrozole belongs to a class of medications called nonsteroidal aromatase inhibitors. It works by inhibiting the production of the hormone estrogen by blocking aromatase, an enzyme that converts the hormone androgen into small amounts of estrogen. This mechanism results in lesser estrogen available to stimulate the growth of breast cancer cells.

What is the Effect of Unbalanced Aromatase?

Unbalanced aromatase is associated with fluctuations in estradiol, the main form of estrogen. Although estradiol production is a common problem in women, men also need to maintain balanced levels of this hormone. Since men do not have ovaries (where large amounts of estradiol are produced), estradiol in men is produced in fat cells, liver, and testicles through a complex process that requires aromatase. For optimal health, men and women should have an estradiol level of 18-30 picograms per milliliter (pg/mL).

As men age, aromatase activity in their bodies dramatically increases, resulting in higher estradiol and lower testosterone levels. Aside from old age, men on testosterone replacement therapy (TRT) can also experience an increase in estradiol and dihydrotestosterone (a stronger version of testosterone). Elevated levels of estradiol can cause unpleasant symptoms in men such as:

• • Benign prostatic hyperplasia (BPH)
  • Decreased muscle mass
  • Emotional disturbances such as anxiety and depression
  • Enlarged breasts (gynecomastia)
  • Fatigue
  • Increased abdominal fat
  • Sexual dysfunction (decreased libido and erectile dysfunction)
  • Type 2 diabetes

On the other hand, men can also produce too little aromatase, resulting in low estrogen levels. This causes serious health problems such as:

• Bone problems
• Depression and anxiety
• Erectile dysfunction
• Fatigue
• Increased body fat
• Irritability

Chemical Structure of Anastrozole

Research on Anastrozole

A. Combats Cancer

Anastrozole is known as a potent anti-cancer drug. Strong scientific evidence shows that this nonsteroidal aromatase inhibitor is effective against various types of cancer:

1. In postmenopausal women with advanced breast cancer, significant survival advantage and improvement in quality of life parameters were observed in subjects treated with anastrozole at 1 mg/day. [1]
2. In postmenopausal women with early-stage breast cancer, treatment with anastrozole beyond 5 years further reduced the risk of breast cancer recurrence. [2]
3. Phase III clinical trials have also demonstrated that anastrozole dramatically delays tumor progression compared with tamoxifen, an anti-estrogen drug, in postmenopausal women with advanced estrogen-receptor-positive breast cancer. [3]
4. Anastrozole treatment at doses of 1 and 10 mg once daily has also been found to be effective in the treatment of postmenopausal women with advanced breast cancer who benefited from tamoxifen treatment. [4]
5. Long-term follow-up data from the ATAC (Anastrozole, Tamoxifen Alone or in Combination) trial confirmed the efficacy of anastrozole in the treatment of hormone-sensitive early breast cancer in postmenopausal women. [5]
6. A study found that anastrozole has been used in the chemoprevention and treatment of early-stage breast cancer in postmenopausal women. [6]
7. A cell study found that treatment of tumor cells with anastrozole led to significant suppression of tumor cell growth. [7]
8. Studies found that anti-estrogen treatment is associated with a significant reduction in lung cancer mortality. [8-9]
9. In postmenopausal women with advanced non-small cell lung cancer, anastrozole slowed the time to when cancer progressed. [10]
10. In a postmenopausal woman with advanced breast cancer which spread to the lungs, anastrozole treatment resulted in marked regression of the lung tumor. [11]
11. In an animal model of lung cancer, anastrozole combined with ibuprofen showed enhanced anti-tumor effects. [12-13]
12. A cell study found that anastrozole induced growth suppression and cell cycle arrest of breast cancer cells. [14]
13. A 2017 study published in Saudi Medical Journal found that anastrozole showed anti-cancer activities against breast, liver, and prostate cancer cells in a dose-dependent manner. [15]
14. In women who took anastrozole 1 mg per day for 5 years, a 49% reduction in breast cancer was observed. [16]
15. In postmenopausal women, anastrozole has been found to have a more favorable overall risk-benefit profile and lower recurrence rate of breast cancer than tamoxifen. [17]
16. In postmenopausal women with breast cancer, treatment with anastrozole at 1 mg or 10 mg once daily for 28 days improved symptoms by reducing estrogen levels. [18]
17. The International Breast Cancer Intervention Study II (IBIS-II) trial found that anastrozole can help reduce the risk of breast cancer in postmenopausal women with an increased risk of cancer. [19]
18. A review of several clinical trials found that anastrozole has superior efficacy to tamoxifen in the treatment of early breast cancer. [20]
19. In postmenopausal women who are at increased risk for breast cancer, treatment with anastrozole at 1 mg/day in addition to chemotherapeutic drugs has been recommended as the standard therapy. [21]
20. When combined with testosterone therapy, anastrozole significantly reduced the growth and multiplication of human breast cancer cells. [22]

B. Increases Pregnancy Rate

High-quality studies assessing the benefits of anastrozole on women’s fertility have shown that this nonsteroidal aromatase inhibitor can induce ovulation and increase the chances of getting pregnant:

1. In women with polycystic ovarian syndrome who are resistant to the fertility medication clomiphene, anastrozole induced ovulation and is associated with a 15.1% pregnancy rate. [23]
2. A 2013 study published in the Journal of Clinical Endocrinology & Metabolism found that anastrozole is effective at inducing ovulation in patients with polycystic ovarian syndrome and unexplained infertility. [24]
3. Studies found that women treated with anastrozole had a higher pregnancy rate compared with subjects who received clomiphene citrate. [25-27]
4. In women with endometriosis-associated infertility, anastrozole increased the pregnancy rate by 45% via inhibition of the growth of endometriotic cells. [28-29]
5. A study showed that anastrozole does not only increase the pregnancy rate in women with endometriosis but it also helps relieve unpleasant symptoms such as pain and bone problems. [30]
6. In infertile women, treatment with 1 mg of anastrozole daily resulted in favorable pregnancy outcomes. [31]
7. In clomiphene-resistant women with polycystic ovarian syndrome, anastrozole increased ovulation and pregnancy rate. [32]

C. Improves Sperm Quality

In men, anastrozole can be considered a therapeutic option for infertility. A great deal of evidence suggests that this drug has the capacity to improve various sperm parameters:

1. In infertile men with low sperm count, anastrozole treatment resulted in an improvement in sperm concentration, motility (the ability of sperm to move and reach the egg), and structure. [33]
2. A study found that anastrozole can treat male infertility by raising testosterone levels. [26]
3. A 2018 study published in BJU International found that combination therapy with anastrozole and clomiphene citrate is a safe and effective alternative for subfertile men with elevated estradiol levels or low testosterone: estradiol ratio. [34]
4. In men with low sperm count, semen analysis before and during anastrozole treatment found an increase in semen volume, sperm concentration, and motility index. [35]
5. In men with low testosterone levels, treatment with 1 mg anastrozole daily significantly improved sperm parameters. [36]
6. A 2012 study published in Fertility and Sterility found that treatment with 1 mg anastrozole orally every day for 6 months improved both hormonal and semen parameters in men with abnormally low sperm count. [37]
7. A study found anastrozole (1 mg once daily) can treat male infertility by increasing the production of mature sperm cells (spermatogenesis). [38]
8. In men with infertility secondary to morbid obesity, treatment with anastrozole normalized blood testosterone levels and spermatogenesis. [39]
9. In men with low sperm count and men without sperm, anastrozole treatment resulted in a higher success rate of in vitro fertilization. [40-41]

D. Improves Body Composition

Evidence suggests that anastrozole may exert beneficial effects in people with obesity as well as those with muscle wasting through increasing lean muscle mass:

1. In women with breast cancer who were undergoing chemotherapy, anastrozole treatment resulted in an increase in lean body mass and free testosterone levels. [42]
2. In patients with morbid obesity, anastrozole and other aromatase inhibitors reversed the deposition of abdominal fat. [43]
3. In animal models, the combination treatment of aromatase inhibitors and testosterone led to a significant decrease in body fat mass. [44]

Associated Side Effects of Anastrozole

Anastrozole side effects are very uncommon. There have been some side effects associated with the use of this drug wherein the patient had one of the issues listed below at some point while being on anastrozole. However, these side effects weren’t confirmed to be associated with the treatment and could have been a coincidence and not related to the use of anastrozole. Despite this, it was listed as a side effect associated with anastrozole even though these associated side effects are very uncommon.

Side effects associated with anastrozole may include the following:

• Blurred vision
• Bone pain
• Chest pain or discomfort
• Dizziness
• Headache
• Nervousness
• Pounding in the ears
• Slow or fast heartbeat
• Swelling of the feet or lower legs

References

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