San Antonio Breast Cancer Symposium 2013- Anastrazole Studies

So here we are, day four at the San Antonio Breast Cancer Symposium and we remain amazed at the wealth of information presented at this conference from around the world. While there were many interesting studies presented, I couldn’t possibly keep up with all the information but I would like to share three very interesting studies that have to do with anastrazole, used commonly in post menopausal women.

Anastrozole, an aromatase inhibitor that prevents the body from making estrogen, has been used to treat postmenopausal women with hormone receptor-positive breast cancer for more than a decade. About 80 percent of women diagnosed with breast cancer in the U.S. each year have tumors with high levels of hormone receptors. That means that their tumor feeds off of the estrogen, allowing it to grow.

The International Breast Cancer Intervention Study II Prevention trial examined 3,864 postmenopausal women ages 40-70 who were at increased risk for developing breast cancer, primarily because of family history. In the double-blind, randomized trial, half the women received the drug anastrozole, while the other half received a placebo. After a little more than five years, researchers found that the women who received the drug were 53 percent less likely to have developed breast cancer compared with women in the placebo group.

The predicted cumulative incidence of breast cancer after seven years was 5.6 percent in the placebo group and 2.8 percent in the group receiving the drug.
The women taking anastrozole (brand name Arimidex) reported increases in muscle aches, stiffness of the joints, and pain, but these were common in the placebo group as well. There was also a small increase in bone fractures. Researchers also had an unexpected finding: about 40 percent reduction in other cancers, mostly skin cancers.

So this is good news right? What promising news for women to know that we can use this drug for prevention of breast cancer. What do we do with the side effects, the aches and pains or athralgias? Even though the placebo group also had complaints of athralgias, we have to consider the audience. We post-menopausal women are aging and could experience aches and pains from other causes. The athralgias cannot be dismissed because they are real for these women and lead to 20% discontinuation rate in the first year of therapy and reports of 40% of women not taking the anastrazole daily.

The  hormones and physical exercise (HOPE) study was conducted to show the effect of regular exercise over one year compared to normal follow-up and education. The study participants had to already have the side effects of athralgias and had been on anastrazole for at least six months.  Moderate exercise, which consisted of twice weekly strength training and 2.5 hours a week of moderate intensity aerobic exercise, decreased the incidence of athralgias by 30%. The improvements in pain were better than the relief obtained by glucosamine, Vitamin D, and acupuncture.
Additional benefits achieved:

  • Increased muscle strength
  • Increased musculoskeletal injury
  • Improved aerobic conditioning
  • Improved range of motion
  • Weight and body fat loss
  • Decreased systemic inflammation levels
  • Improvement in pain thresholds

This was a great study proving the many overall benefits of exercise in this group of patients. I believe we will see many more of these types of studies and it is about time.

The third anastrazole study I wanted to mention looked at the change from brand to generic aromatase  inhibitors and hormone therapy adherence for early stage breast cancer.  The study considered the effect on patient adherence when patients are offered this therapy but a a lower copay now that the drug was available as a generic.  The study identified the varying costs patients were having to pay for this drug based on differences in insurance coverage.  The study showed that out-of-pocket costs do impact patient decisions to continue or discontinue the therapy.  Also noted was that patient survival after breast cancer may be improved by better access to this drug.  The lead researcher appealed for support of the Cancer Treatment Fairness Act Bill that would prohibit  higher co-payments regardless of the benefit category.  This bill has already passed through 26 state legislatures.

This is a lot to consider for patients taking anastrazole as it brings out the benefits and challenges of this therapy.

I am going back into the sessions now,
Compass Marie

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