Tuesday, December 22, 2009
Apparently the “several top cancer doctors” interviewed by the New York Times (about a couple of recently presented studies suggesting that oral bisphosphonate drugs, such as Fosamax, prevent breast cancer in some women) haven’t been keeping up with the literature in their field.
To be sure, in a scientific vacuum, their skepticism would be warranted. They rightly point out that one should be cautious interpreting data associations in the absence of randomized studies, which these are not. Women choosing to take bisphosphonates are those with weaker bones, which may have been caused by lower estrogen in the first place. Lower estrogen also reduces risk for hormone-positive breast cancer, so lower breast cancer and use of oral bisphosphonates may simply have low estrogen in common; thus there could be no direct causal effect of taking oral bisphosphonates.
But the data did not emerge in a vacuum. For example, it has been known for some time now from randomized trial data (Gnant et al, 2008) that breast cancer patients taking the closely related drug zoledronic acid (Zometa) (which is taken intravenously rather than orally) have somewhat fewer cancer recurrences than comparable patients who do not. In fact, zoledronic acid was originally used to treat cancer patients with bone metastases, and has only secondarily been prescribed for osteoporosis.
So, it is quite possible that there is indeed a preventative effect being seen in the observational studies with oral bisphosphonates, despite the problems of interpretation associated with non-randomization.
But even if it can be shown that bisphosphonates help prevent cancer, that doesn’t necessarily mean everyone should take them. As with all drugs, there are risks that anyone considering medication should discuss with her doctor. Unfortunately our cultural yearning for cure-all drugs, stoked to a high-stakes quest by pharmaceutical companies trying to make a profit, will likely lead to a distorted interpretation of the data that results in these drugs being pushed hard on all older women. Already, far more women take bisphosphonates than really need them for bone health, partly due to clever manipulation of the definition of “disease” by drug companies. No doubt because of this announcement we will see shortly another big push to get as many more women as possible on these drugs.
I have already heard at least one doctor assert that every single American should be on statins, because they prevent heart disease in a subset of adults. But if there were a pill to prevent each disease you could possibly get in your lifetime, would you take them all? A hundred pills would certainly not be practical, but would you draw the line? Where should doctors and insurance companies draw the line? People who claim loudly to believe in unlimited health “care” (i.e., are anti-”rationing”), would perhaps believe there should be no line. Just remember, though, that drug companies absolutely support that view, but not so much for philosophical reasons. Drugs such as bisphosphonates and statins may or may not benefit a particular individual, but every individual taking them absolutely benefits the drug company. It’s a fine, blurry line between health and profit.
Reference:
Gnant M, Mlineritsch B, Schippinger W, Luschin-Ebengreuth G, Poestlberger S, Menzel C, Jakesz R, Kubista E, Marth C, and Greil R. 2008. Adjuvant ovarian suppression combined with tamoxifen or anastrozole, alone or in combination with zoledronic acid, in premenopausal women with hormone-responsive, stage I and II breast cancer: First efficacy results from ABCSG-12. Journal of Clinical Oncology 26 (May 20 suppl; abstr LBA4)
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