Read Original Release

No data to back up claim that soy, kale and broccoli reduce breast cancer treatment side effects

Soy, cruciferous vegetables associated with fewer common breast cancer treatment side effects – Georgetown University Medical Center

Our Review Summary

This news release rather thinly describes a study designed to demonstrate whether chemicals naturally found in soy-based foods and cruciferous vegetables such as broccoli and kale are linked to reduced side effects of hormone-related treatments among breast cancer survivors.

Although the release ably describes some of the reasons the dietary intervention might work and how, it offers no numbers or measurements to support the conclusion that these foods are associated with fewer menopausal symptoms such as fatigue and hot flashes. Nor does it describe how dietary data were collected, and thus how reliable they are. While it aptly cautions breast cancer patients not to start a soy-rich diet until further research is done, it doesn’t say why caution is recommend. Nor does it describe just how much of these foods might be considered beneficial or harmful in a normal diet.


Why This Matters

So-called “chemoprotective” or “chemopreventive” components such as sulforaphanes found in broccoli sprouts and in soy products have for decades been the subject of studies designed to link them to lower prostate and other cancer rates and to other health benefits. If in fact dietary interventions can be shown to reduce common side effects of breast cancer treatments — particularly those that affect estrogen — women might be more interested in long-term therapies that suppress female hormones, and also greatly improve the quality of their lives. Thus, studies like this one are likely to make news, but readers need information that offers context, and the potential downsides as well as upsides.


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

Not Satisfactory

While dietary interventions often are considered inexpensive, they are not free. The cost of adding cruciferous veggies and soy products to the shopping lists of potentially millions of women is worthy of a mention.

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

Not Satisfactory

Beyond vague descriptions of benefits such as “fewer reports of menopausal symptoms,” the news release does not offer any meaningful measure of what the patient’s symptoms were at the beginning of the study and how much symptoms were reduced among those who ate “more” of the soy and cruciferous vegetable diets. It also isn’t clear on which menopausal symptoms were decreased.

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


The release responsibly devotes some attention to harms. It notes that in preclinical animal studies, “biologically active compounds present in both soy and cruciferous vegetables cause breast cancer cells to grow, but have opposite effects in animals that consume these compounds well before cancer is diagnosed and continue consuming them during and after cancer treatments.”

It also cautions that breast cancer patients shouldn’t start eating soy now if they haven’t consumed it previously, noting that more research is needed to understand potential risks.

Numerous studies have examined the impact of soy-based foods on women with breast cancer — with conflicting results — and we expect this debate will continue. Some recent studies suggest that eating soy, benefits women with breast cancer, particularly at the low rate it is consumed in the American diet.

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

Not Satisfactory

Readers really would have benefited from some numbers in this release, particularly how the researchers measured diets, the range of reduced symptoms, and the number of women who experienced what range of symptoms and symptom reduction. None of that is included, nor would readers with cancer learn enough about the study population (the age range of the study participants, what stage of cancer, kinds of therapy, etc.) to make any sense of how or whether the findings relate in some way to their own experiences.

We did appreciate the framing of the headline and lede which states soy is “associated” with reduced symptoms. The release avoids overstating the benefit — something we see all too often in news releases.

Does the news release commit disease-mongering?


No mongering. But more detail on the number of women who experience menopausal symptoms as side effects from cancer treatments beyond saying they “often” do would help put the problem in context.

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


There was disclosure of the funding sources, and the release tells us that the study authors had no financial conflicts of interest. Good job.

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

Not Satisfactory

The news release could have noted whether or not most women’s symptoms resolve over time, and whether there are non-dietary means of reducing or coping with symptoms. There was no mention of any of the existing alternatives for helping reduce menopausal symptoms including medications and lifestyle changes.

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

Not Applicable

It’s understood that soy and cruciferous vegetables are found in basically all grocery stores so we’ll rate this Not Applicable.

However, there needs to be more recognition that people who live in “food deserts” across the country — urban areas with limited access to affordable and fresh vegetables — cannot so easily access healthy food. 

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


The release does a pretty good job of explaining “what’s new” about the study, particularly as it relates to the study population. We can’t be sure how generalizable the results are to all breast cancer patients.

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


The authors didn’t use unjustifiable language and did mention that more research is needed to confirm their study findings.

Total Score: 5 of 9 Satisfactory


Please note, comments are no longer published through this website. All previously made comments are still archived and available for viewing through select posts.