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Can omega-3s really lower breast cancer risk? PR release touts subgroup, ignores main study outcome

Omega-3 Fatty Acids May Lower Breast Cancer Risk in Postmenopausal Obese Women

Our Review Summary

Omega 3 capsuleThis release describes the results of a study testing whether omega-3 fatty acids have a beneficial effect on reducing the risk of breast cancer in obese women by reducing the density of their breast tissue. Higher breast tissue density is recognized as a marker for increased breast cancer risk. The study involved a small group of women who received the omega-3 fatty acid, the omega-3 in tandem with a chemo-preventative drug Raloxifene, the drug alone, or no treatment at all.  According to the release, at the end of two years, women considered obese (their body mass index — BMI — was greater than 29) showed a reduction in breast tissue density, which the researchers argued reduced their cancer risk. However, this is misleading. This finding is from a small subgroup of obese women within the already-small study. The main finding of the study — which is never even mentioned in the news release — is that the supplement had no impact on reducing high breast density whether taken alone or in tandem with Raloxifene. The release also omitted projected costs and harms of the prescription-only supplement used in the study.

 

Why This Matters

The American Cancer Society predicts that 246,660 new cases of invasive breast cancer will be diagnosed in women this year and that more than 40,000 women will die from this disease. Easy actions that women can take to prevent this disease, or at least reduce their risk of getting it, are of almost universal interest to the public. If it is shown that taking a readily available supplement like omega-3 fatty acids will reduce breast cancer risk in obese women, that’s information that will be of wide interest.

Criteria

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The release makes no mention of costs although omega-3 fatty acid supplements are readily available across the market.  A quick web search shows that a month’s supply of Lovaza, the omega-3 fatty acid used in this study, will cost about $280 per month, or $3.360 a year, a hefty price for most Americans.

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

Not Satisfactory

The headline states,”Omega-3 Fatty Acids May Lower Breast Cancer Risk in Postmenopausal Obese Women,” and the opening paragraph follows with basically the same statement. But nowhere in the release does it explain how much this supplement may lower a woman’s risk. It says that breast cancer density is a biomarker for breast cancer risk and that obese women taking the supplement had a reduction in tissue density after two years but no details to back up the claim. In stories and releases focusing on cancer risk, the public wants, and rightly deserves, real numbers so that they can make informed decisions. This release only offers a vague prediction of risk reduction. Lastly, the release states that the omega-3s “may lower” the cancer risk, but readers could just as easily conclude that it “may not” without more information.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

This release fails to mention harms at any point and, while a widely consumed, readily available supplement like omega-3 fatty acids isn’t likely to cause major problems, it is not free from side effects that are worth mentioning. The research paper itself points to more than a half-dozen participants in the study who withdrew because of adverse effects including hot flushes, leg cramps and nausea. Readers rightly deserve to know possible negative impacts found in research studies.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The published research states that in the original study design, researchers didn’t find a difference in changes in breast density in any of the treatment arms.

In the overall cohort of healthy postmenopausal women, the administration of n-3FA (a combination of 1,860 mg of EPA and 1,500 mg of DHA daily) alone or in combination with the antiestrogen raloxifene did not reduce breast density, a well-established biomarker of breast cancer risk.

However, you’d never even know this from reading the news release, which presents the findings of a small subgroup as if they were the main results of the study. The significant result they found was only in women with a BMI greater than 29 (“using an adjusted statistical model, we show a significant negative correlation between plasma DHA breast density only in women with BMI > 29.”)

This is an important distinction since the original study was not powered based on distribution of BMI. If 20 percent of the sample was obese (BMI over 29) that would be about 10 subjects per arm of the study that were obese.The release falls short in at least two other simple descriptions of the research. First, it mentions that “the study included 266 healthy postmenopausal women” while the research paper clearly points out that only 214 women completed the clinical trial — something not addressed in the news release. Also, in its description of how the research was done, the release mentions that women were divided into four groups while in fact, they were separated into five groups. The release fails to mention two differing doses among the women receiving the drug Raloxifene.

There is one more concern regarding the release’s presentation of the study results. The researchers note in the manuscript that other trials have found that Raloxifene does not have an effect on breast density although it could have an effect on breast cancer risk.

Does the news release commit disease-mongering?

Satisfactory

The release doesn’t engage in disease-mongering.

Does the news release identify funding sources & disclose conflicts of interest?

Satisfactory

The release does identify the funding sources for this research as well as the suppliers of the drugs used in this study so possible conflicts of interest are adequately addressed.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

The release makes no mention of any other approaches to reducing the potential risk of developing breast cancer although some preventative actions are readily known and could have been included. These include limiting alcohol, not smoking, controlling weight, breast-feeding and exercising.

Since the focus of the research was on reducing risk by reducing breast density the most obvious alternative to taking omega-3 supplements is losing weight through diet.

Does the news release establish the availability of the treatment/test/product/procedure?

Satisfactory

The release notes that the omega-3 fatty acid supplement used in this study, Lovaza, is FDA approved and requires a prescription from a physician.

Does the news release establish the true novelty of the approach?

Satisfactory

The release makes no evident claim of novelty. We’ll give it a pass for reinforcing in at least two places that the research builds on previous research and the understanding that highly dense breasts are associated with greater risk for breast cancer.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Satisfactory

The release does not use any explicitly unjustifiable language. We do have concerns that the release suggests, particularly in the headline, that there’s a method that “may” reduce breast cancer risk but then fails to provide reasonably expected data to back up the claim.

Total Score: 5 of 10 Satisfactory

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