As estrogen is a known risk factor for some forms of breast cancer, there has been some concern that plant-based compounds with weak estrogen-like effects called phytoestrogens may increase the risk of breast cancer in women.

Studies investigating a possible association between phytoestrogens and breast cancer risk have yielded mixed results. Interestingly, some of the best data seems to suggest that some phytoestrogens may actually reduce the risk of breast cancer.

For example, a new German study found that regular consumption of three particular phytoestrogens was associated with a reduced risk of breast cancer in post menopausal women: soy foods (17% reduction) sunflower and pumpkin seeds (34% reduction).

The study consisted of 2,884 postmenopausal women diagnosed with breast cancer and 5,509 age-matched “controls” without breast cancer. Each filled out detailed food-frequency questionnaires and answered additional questions regarding consumption of specific phytoestrogen-rich foods. Each woman’s individual risk factors for breast cancer were also assessed and considered when analyzing the data.

Unanswered Questions

From this study it appears that at least some forms of phytoestrogens may be beneficial, even though they act on some of the same hormone receptors that estrogen normally stimulates. While this may seem counterintuitive, it supports other research that suggests that phytoestrogens are more complex than once thought.

In fact, some believe that phytoestrogens may actually block the effects of estrogen on estrogen receptors within breast cells. We’ll need more research to understand the exact cause and effect of phytoestrogens on breast cancer.

Sources:

PubMed

Dr. Robert Wascher

In recent years there has been much discussion and conflicting opinions about when and how often women should be screened for breast cancer. Specifically, the 2009 U.S. Preventive Services Task Force touched off a wave of controversy when it recommended screening mammograms every two years starting at age 50. The previous standard for women was a baseline mammogram at age 40 and then regular screening every year or every two years following.

The task force rationale was that mammograms for average-risk women in their 40s posed considerable harms, such as false-positive results causing anxiety or leading to unnecessary invasive procedures.

Instead, they suggested that women in their 40s who were at average risk of breast cancer should discuss the pros and cons with their doctors and then decide about the value of screening. Meanwhile other organizations, including the American Cancer Society, continued to advise women 40 and older to get yearly screening mammograms.

This left 40-something women and their doctors without concrete answers, such as: What risk factors make early screening worth the risk of unnecessary procedures and associated cost?

New Insights

Two new studies set out to help quantify the risk/benefit ratio of mammograms for women with various risk factors. They found that women who have a family history of breast cancer or unusually dense breast tissue, should have their first test at age 40 and repeat the exam at least once every other year.

The first study analyzed data from 66 published studies to identify specific factors that increased breast cancer risk for women ages 40-49. Of 13 possible risk factors, they found extremely dense breast tissue or a direct relative with breast cancer (parent, sibling or child) doubled the risk of breast cancer in women 40 to 49. Breast density is determined by mammography.

About 13 percent of women in their 40s have extremely dense breast tissue and 9 percent have a first-degree relative with breast cancer.

Then they used computer modeling to predict the outcomes of 44,000 simulated women based on two scenarios: having their first mammogram at age 50 or at age 40. They then compared the rates of false alarms, breast cancer diagnoses and mortality in both groups.

The computer models indicated that higher-risk women 40 to 49 who start every-other-year screenings at age 40 have the same benefit-harm ratio as average-risk women 50 to 74 who have mammograms every two years.

In the course of their study, the researchers also found small differences in benefits between film mammography and the newer digital mammography. The digital forms had more false-positives.

Sources:

LA Times

Health Finder

Among breast cancer myths the concern that there may be a connection between deodorant use and breast cancer still persists. While a new study may finally let deodorants off the hook, one of its suspect ingredients may still be a cause for concern.

For many years, deodorants fell under suspicion for a few reasons:

• Most breast cancers are located in the outer, upper quadrant of the breast near the arm pit where deodorant is applied. The feeling was, “This couldn’t be a coincidence, right?”
• Parabens and aluminum, ingredients in some underarm products, were found in breast cancer tissue and both have weak estrogenic effects. And since estrogen is a risk factor for breast cancer, deodorants were suspect.

The latest study conducted by Dr. Philippa Darbe, who has been researching a possible connection between parabens and breast cancer for several years, found parabens in the breast tissue of women who had never used deodorants.

Darbe examined breast tissue samples from 40 women who had mastectomies and found widespread traces of parabens in breast tissue—even in the seven women who said they never used underarm products. Parabens were found in 158 of the 160 samples taken from the tissue collected from the 40 women. They found 96 samples contained all five of the most common paraben esters (forms).

The levels of paraben were four times higher than a similar study she conducted in 2004. This was a surprise as many manufacturers removed parabens from underarm products as a result of her 2004 study.

Darbe is quick to point out that her studies only reported the presence of parabens in breast tissue, not that parabens caused breast cancer. "I feel sure the issue is bigger than one chemical," she said. And, as many body lotions, sunscreens and cosmetics contain parabens, deodorants cannot be singled out. She believes that parabens in breast tissue come from a variety of sources.

Until more research is conducted to understand if parabens and other endocrine disruptors affect breast cancer risk, she suggests we cut back the use of cosmetic products as much as possible. "We simply use too much in the modern world -- too much for our body systems and too much for the wider environment," she said.

Other cancer experts echo Darby’s comments. The American Cancer Society finds no clear link between deodorant/antiperspirants and breast cancer. They note that, "There are no strong epidemiological studies in the medical literature that link breast cancer risk and antiperspirant use, and very little scientific evidence to support this claim." They add that Darby’s and other studies do establish that parabens found in topical skin products can be absorbed through the skin. The American Cancer Society maintains that more and larger studies are needed to find out what, if any, effect parabens might have on breast cancer risk.

Paraben Controversy Persists

The cosmetic industry continues to assert that parabens are safe and effective preservatives. They argue that:

• Parabens occur naturally in foods and are safely metabolized by the body and flushed out.
• They have very weak estrogenic activity compared to stronger estrogens in birth control pills, estrogen replacement therapy and natural phytoestrogens found in soy, red clover, and hops.

However, a recent study found that parabens act much differently when absorbed through the skin. When applied topically, parabens inhibit an enzyme called SULT that helps the body flush out estrogen. So, when SULT enzymes are deactivated, estrogen levels increase. These results suggest that chronic topical application of parabens may lead to prolonged estrogenic effects in skin as a result of reduced SULT activity.

As for whether parabens are metabolized when applied to the skin, another study found that after a month of applying methylparaben to skin cells, it "remained unmetabolized and persisted slightly" in the outermost layer of the skin. Additionally, it was found to affect DNA expression in the skin cells, inhibiting collagen production, and possibly leading to early aging of cells. 

For more on other suspect ingredients in cosmetics, see The Real Cost of Beauty:  Dangerous Toxins Lurking in Your Cosmetics.

Sources:

HealthDay

PubMed

Skin Inc

PubMed