Medical experts are saying that research just released from the medical journal the lancet will have a profound impact on many women battling breast cancer. It shows that one of the most popular and established drugs should be replaced by newer medicines.

This study compared two drugs approved for treating postmenopausal women with breast cancer: the drug tamoxifen, which is the main drug used now, and another called arimidex.

Women with the type of breast cancer normally treated with the popular drug tamoxifen--namely hormone sensitive breast cancer, or hormone receptor positive cancer, could instead benefit from the class of drugs called aromatase inhibitors. There are three of these drugs on the market here in the U.S.

Now, a study released by the journal The Lancet and presented at a major breast cancer meeting, showed one, arimidex, could be a more effective drug than tamoxifen with fewer side effects. In many cases, estrogen and progesterone in the body are in fact fuel to breast cancer, causing the tumor to grow and spread. Tamoxifen is hormonal therapy that blocks the ability of these hormones to get to the cancer and thus slows it’s growth, spread, and recurrence.

Arimidex works differently: it blocks the production of estrogen. The new five year data shows arimidex, compared to tamoxifen, increased disease free survival by over ten percent. It increased the time it took for the cancer to recur by around 20 percent and reduced the spread of cancer by 14 percent and reduced cancer occuring in the other breast by 40 percent.

Dr. Steven Malamud, a cancer specialist at Beth Israel Medical Center in New York, says, “Having a drug that is at least equivalent and probably better than tamoxofin with a much more acceptable side effect profile, is a drug that is going to be very clammered for by our patients and very much accepted opposed to the standard therapies.”

Arimidex was associated with fewer side effects. With tamoxifen, there is some increased risk for cancer of the uterus. Blood clots have been reported in the veins of a small percentage of patients who take tamoxifen along with chemotherapy. Bone fractures and joint pain were more common among women given arimidex.
Overall, fewer women given arimidex stopped taking the tablets early compared with women given tamoxifen.

“For the woman who had been on the tamoxofen and is at that five year mark…they should be talking about a conversion over to an aromatase inhibitor with their physicians to see if they are appropriate candidates for that,” states Dr. Malamud. The authors say that five years of arimidex should now be considered as the preferred initial hormonal treatment for postmenopausal women with hormone-receptor-positive localised breast cancer.

The National Cancer Institute estimates that 13.4 percent of women born today will be diagnosed with breast cancer at some time in their lives.

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