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Studies: Bone drugs may help prevent breast cancer


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Studies: Bone drugs may help prevent breast cancer

Our Review Summary

This story covers the results of preliminary findings of two large observational studies presented at the San Antonio Breast Cancer Symposium which suggest that bisphosphonates, for example Fosamax, Boniva and Actonel, may play a role in reducing the risk of breast cancer.   This story was informative and provided a high level of detail about how the studies were designed.  It presented results in both relative and absolute terms.  The story described the significance of the research but clearly indicated that role of bisphosphonates in breast cancer prevention is an unfolding story that requires further investigation.  


Why This Matters

Breast cancer is the second leading cause of cancer-related death in women, following lung cancer.  Currently, there are no preventive measures for women of average risk.  The research results reported in this story add to other recent studies that have created interest in the potential roles of bisphosphonates – which are taken by millions of women with bone loss and osteoporosis – in reducing cancer risk. 


Does the story adequately discuss the costs of the intervention?


This story informs the reader of the cost range for some generic and brand name drugs.  It states that a 3-month supply of alendronate, a generic version of Fosamax, costs about $100 and that biannual infusions of the Novartis drug Zometa costs up to $1,200.  Although it is not stated, these are estimated retail costs. 

Does the story adequately quantify the benefits of the treatment/test/product/procedure?


This story does a good job of presenting potential benefits in detail, including the number of women in each study, the study design and factors that need to be taken into account when considering the results.  Results are presented in both relative and absolute terms.  For example, one of the studies reported about a 30% decreased incidence of developing invasive breast cancer over about 8 years in women who took oral bisphosphonates compared to those who did not.  The story explains that in absolute terms, for every 1,000 women taking bisphosphonates for one year there would be one less case of invasive breast cancer. 

Does the story adequately explain/quantify the harms of the intervention?


The story mentions some of the potentially severe side effects of bisphosphonates including bone, joint or muscle pain and, in rare cases, jawbone decay.   The story also mentioned that one of the studies showed a slight increased risk of noninvasive tumors in women who took bisphosphonates compared to those who did not.  It could have also mentioned that gastrointestinal distress is another potential side effect, but did confirm that bisphosphonates are generally well-tolerated.

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The story should have emphasized that this was an observational study and  that the association is just that — an association, not cause and effect.  Women who develop osteoporosis tend to be women who may have lower breast cancer risk to begin with, perhaps due to lower circulating estrogen levels.  This concern was addressed in a New York Times story the same studies:

"…several top cancer doctors expressed skepticism about the findings, saying they prove only an association and may reflect the fact that women with bone problems who are most likely to take the medications have a lower breast cancer risk to begin with."

“We’re reporting an association,” said the study author, Dr. Gad Rennert of the Technion-Israel Institute of Technology. “If the story is right and true — and I’ll repeat this 100 times, because in science you never know, I think it is but I can’t guarantee it — it’s quite meaningful.”

"experts warn there is ample reason for caution in interpreting the new studies. Older women who take oral bisphosphonates generally do so because they have low bone mineral density. But women with that condition may be at lower risk for developing breast cancer in the first place; their bone problems are believed to stem from lower estrogen levels, and breast cancer risk increases with higher lifelong exposure to estrogen."

Instead, the AP story only briefly mentioned limitations before turning back to "hopeful buzz":


The study is not enough to prove that these drugs, called bisphosphonates, prevent cancer. More definitive studies should give a clearer answer in a year or two.

Yet it greatly amplifies the hopeful buzz that started last year when researchers reported that a bisphosphonate cut the chances that cancer would come back in women already treated for the disease.


Does the story commit disease-mongering?


Overall, the story tempers hopes with a sufficient amount of factual information on what has, and has not, been shown.  It does go back and forth a bit in the language used to address the topic.  For example, it talks about the ‘exciting possibilities’ and ‘hopeful buzz’.  This is countered by a statement that recent research results are ‘not enough’ and that these drugs should not be taken for cancer prevention. 

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

This story provides perspectives from two independent medical experts and states that one of these experts has no financial ties to any of the drug makers.  It addresses potential conflict of interest by noting that the lead scientists for one of the featured research studies reported consulting for pharmaceutical manufacturers. 

But it did not include any quotes expressing any reservations or skepticism, as the New York Times did in its story with these expert quotes:

“These are provocative data, but certainly not compelling, and not definitive.” (said Dr. Gabriel N. Hortobagyi, who directs the breast cancer research program at the University of Texas M.D. Anderson Cancer Center.)

Other breast cancer experts agreed. “If in fact you have osteoporosis and you’re taking these drugs, it’s possible there is an added benefit,” said Dr. Eric P. Winer, a breast cancer specialist at the Dana-Farber Cancer Institute in Boston. “But at the moment, I don’t think these studies should be used as a reason to take a bisphosphonate to prevent breast cancer. As with all drugs, there are side effects and risks.”

That Winer quote is weaker than the one the AP used:  

"These are drugs that, generally speaking, are relatively well tolerated" and fairly safe, but they still should not be taken for cancer prevention until more definitive studies show their risks and benefits, said Dr. Eric Winer of the Dana-Farber Cancer Center in Boston. He has no financial ties to any makers of these drugs.

Does the story compare the new approach with existing alternatives?


This story notes that the role of bisphosphonates in breast cancer prevention is not known and that these drugs should not be taken as a preventative measure.  It also informs the reader that two drugs, tamoxifen and raloxifene, can be used a preventive measures for women at high risk of breast cancer.

Does the story establish the availability of the treatment/test/product/procedure?


This story is clear that bisphosphonates are widely available and used by millions of women.

Does the story establish the true novelty of the approach?


This story is covering the most recent research that has been reported on the topic of oral bisphosphonates use and risk of developing breast cancer.  These results have not previously been previously reported.

Does the story appear to rely solely or largely on a news release?


There is no evidence that the story relied on a news release.

Total Score: 8 of 10 Satisfactory


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