Anastrozole Arimidex by Ray Sahelian, M.D. Anastrozole breast cancer prevention

Anastrozole is in a class of drugs known as non-steroidal aromatase inhibitors. Anastrozole decreases the amount of estrogen the body makes. This can slow or stop the growth of many types of breast cancer cells that need estrogen to grow. The length of treatment depends on the types of drugs you are taking, how well your body responds to them, and the type of cancer you have.
 

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Anastrozole side effects
Long term use of this drug is indicating that anastrozole side effects do occur with treatment of several years. Treatment for 5 years with the aromatase inhibitor anastrozole is associated with a bone loss of 6% to 7% at the lumbar spine and total hip, respectively. This was the result reported by Dr. Robert E. Coleman at the annual meeting of the American Society of Clinical Oncology. The study examines the effects of anastrozole and tamoxifen on bone health.
   Anastrozole side effect profile overall may be better than tamoxifen; however, as with all aromatase inhibitors, anastrozole is associated with a higher rate of osteoporosis and a greater incidence of fractures compared with tamoxifen. Aromatase inhibitors suppress circulating levels of estradiol, an important regulator of bone health, whereas tamoxifen, at least on bone, acts as a partial agonist.
   The ATAC sub-protocol findings are based on 81 postmenopausal women with breast cancer who took anastrozole and 86 similar women who took tamoxifen for 5 years. After 5 years, anastrozole led to a mean BMD decrease of 6% in the lumbar spine and 7% in the hip, compared with a mean decrease of 2.8% and 0.7%, respectively, with tamoxifen. Results of thee study are of concern to women who have a tendency for osteoporosis. Women treated with aromatase inhibitors may need to make sure they supplement with calcium and vitamin D supplements.

Anastrozole for breast cancer
Tamoxifen or anastrozole may be given as adjuvant treatment to women with early-stage breast cancer to reduce the risk of cancer recurrence. Mature data from the ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial, reported in The Lancet  in 2005 showed that 5 years of anastrozole is more effective in preventing breast cancer recurrence than 5 years of adjuvant tamoxifen.