Dr. Wendy Chen sees the world of breast cancer from two vantage points: from the bird’s eye view of an epidemiologist, scoping out global trends in the risk factors that cause cancer and disease; as well as from the ground-floor perspective of her personal, doctor-patient relationships. Chen is a breast cancer specialist at the Dana-Farber Cancer Institute, where she’s worked since receiving an MD from the University of Pennsylvania and an MPH from the Harvard School of Public Health. She’s also one of the lead epidemiologists on the well-known Nurses’ Health Study. This week, we sat down with Chen to talk about her perspective on healthcare and disease in America.
Q: Where do you focus your research and what drew you to those areas?
I became interested in epidemiology because I was interested in a more holistic view, beyond drug treatment, in preventative measures that impact risk and survival. Specifically, I’m interested in lifestyle and hormonal factors as they apply to a woman’s chances of getting breast cancer, and also improving one’s chances of survival after having breast cancer.
Q: It sounds like that led to your participation in the Nurses’ Health Study. Can you tell us about that large-scale study and how it has progressed?
The Nurses’ Health Study is an ongoing study which looks at healthy behaviors in women and how they impact future risk of disease. Beginning in 1976, 121,700 healthy nurses were given questionnaires every two years, and the study continues today with the same women. Back in 1976, these questions were very basic – about smoking, weight, etc. and their effects on heart disease and cancer. But as the years have gone on, it’s bloomed out into a project that looks across multiple fields, including diabetes and neurological diseases. We examine dietary, physical and lifestyle factors, medication use, etc. In 1989, we started the Nurses’ Health Study 2, and now we are recruiting for Study 3, which will be entirely internet based.
Q: What are some of the conclusions drawn from that study?
The Nurses’ Health Study has led to some landmark guidelines. Trans fats are banned. The guidelines for exercise and maintaining healthy weight were established for cardiovascular health and prevention of cancer and diabetes. Also, the benefits of the Mediterranean diet (one with lean proteins, low saturated fat, low processed sugar, lots of whole grains/legumes) and its association with longevity came out of this study.
Q: How have Big Data Analytics and other technologies transformed this study?
Now, in this era of Big Data, we’ve started to take advantage of some of the new technologies. We are looking at some pilot studies giving people Fitbits, in addition to physical questionnaires. We are also looking at how best to use GPS data. We are already using geo-coded data (we know participant’s addresses), so we can look at the correlation between disease outcomes and pollution.
Q: What lifestyle factors do you believe are involved in breast cancer risk?
Weight is one of them. Women who are heavier after menopause have an increased risk of breast cancer, and this is true for other cancers as well. One serving or more of alcohol a day is associated with an increased risk of breast cancer. Physical activity decreases cancer risk.
A diet very high in fruits and vegetables and carotenoids decreases breast cancer risk. But interestingly, mainly for estrogen-negative breast cancers. The Mediterranean diet decreases risk of cardiovascular disease, and increases longevity for all people, including breast cancer survivors.
Q: We often hear about soy and breast cancer risk, too. Is that something we should consider for our diets?
Soy has a lot of phytoestrogens (plant-based estrogens) and in the lab they can stimulate estrogen activity. However, we’ve looked at this in Chinese and Japanese populations, who consume very large amounts of soy, and if anything the risk of breast cancer is slightly lower. It’s a little difficult to compare these cultures with the U.S. cultures because of the higher consumption of food-based (unprocessed) soy and green leafy vegetables (also high in phytoestrogens) in Asian cultures.
Q: Is fertility treatment a risk in breast cancer?
This is a difficult area for research, because reproductive risk factors – such as age of first full-term pregnancy – influence breast cancer risk and some of those risk factors are related to one’s likelihood of getting infertility treatment. Studies are inconclusive as to whether fertility treatment increases risk of breast cancer.
Q: Let’s talk big picture – how is your field of study and practice evolving?
The research now is more focused on the mechanism of these factors I mentioned in breast cancer risk. So researchers look at, for example, specifically how being overweight and drinking alcohol affect cancer risk. The effects of alcohol use is most likely estrogen-mediated. It’s important to realize that many of the lifestyle factors that I mentioned that lower breast cancer risk are protective against multiple types of cancers and diseases.
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