Scientist in the Spotlight: Patrick Bradshaw, PhD
VIDEO: Patrick Bradshaw talks about
how life doesn't happen in the lab.
We don’t eat single foods or individual nutrients, and deciphering our dietary patterns can tell us a lot about how to prevent cancer, says epidemiologist Patrick Bradshaw, PhD. Bradshaw is one of AICR’s Marilyn Gentry Fellows at the University of North Carolina at Chapel Hill. With a background in biostatistics, his approach of applying novel statistical methods to focus on patterns is helping us learn more about how weight and diet affect cancer risk and survivorship.
Finding Patterns and Systems
Epidemiological research in nutrition and cancer comes with several methodological challenges, including missing data and food interactions. “One of the major limitations of studying diet is that food nutrients are so intertwined and complex, particularly the way we eat them, it’s difficult to tease apart the effect of a single nutrient,” said Bradshaw.
A study he led last year found that consuming a dietary pattern high in vegetables, fruits and lean meats was linked to a lower risk of pharyngeal and oral cavity cancers; a diet high in fatty, fried foods, sweets and processed meats was associated with an increased risk of laryngeal cancer. Using the same cohort, Bradshaw is currently investigating how body size before diagnosis affects survival among individuals with head and neck cancer.
Bradshaw uses that same system-approach to focus on how dietary compounds - rather than individual nutrients - work together to reduce breast cancer risk. In one study, published in Nutrition and Cancer, Bradshaw and his colleagues looked at the actions of 33 nutrients in several recognized metabolic pathways, including those related to antioxidant actions and glycemic control.
The study used nutrient consumption data from about 3,000 women; about half had been diagnosed with breast cancer, and all had completed a dietary questionnaire after diagnosis. Then Bradshaw used a specific type of analysis – called hierarchical modeling – that incorporated biologically plausible actions for each set of nutrients.
The traditional method of analyzing nutrient data is to examine them one at a time, one analysis for vitamin C, one for vitamin E and so on, says Bradshaw. “The trouble is, nutrients tend to be consumed together, so if you see an effect, it’s hard to say which one it was for. If you analyze them simultaneously the statistical models tend to not work well….”
Hierarchical modeling incorporates the known biological activity of the nutrients: “This allowed us to consider many nutrients simultaneously while yielding more precise and plausible estimates,” he said. The analysis found that breast cancer risk was more strongly associated with pathways related to glycemic control compared to the others. “It illustrates how we can apply this methodology to integrate biology into an analysis that looks at a whole lot of things together that can be correlated.”
Weight Maintenance among Survivors
In part motivated by personal connections – Bradshaw's mom is a cancer survivor of over 15 years – he has investigated factors that may affect survivors’ health, such as weight and activity. Last year, he found that breast cancer survivors who gained the most weight post-diagnosis had a greater risk of death from any cause as well as from breast cancer compared to women survivors who remained the same weight at diagnosis.
The reason behind this weight gain among survivors is not well understood, says Bradshaw, and it’s something that he is working to understand.
Another area of survivorship he is focusing on is physical activity. Here, the research is consistent, with most studies finding activity benefits survival, notes Bradshaw, but who is benefiting and how remains unclear. In order to better understand the effects of exercise, he is investigating the effects of physical activity at different times of diagnosis.
Notes Bradshaw: “It looks like women who get physical activity, in particular in those early years of diagnosis, tend to have a better prognosis - they had a reduced mortality rate, which I think could be a powerful message for cancer survivors. I’m really interested in what is happening during those early years. Those are the formative years in terms of breast cancer survivorship.”
The Power of Food
Researching how the foods we eat affect cancer risk fits into a long-held appreciation he has for how much power food can have in our lives, which he learned from his mother and grandmother. That translates into a love for food, eating healthy and cooking.
“I would like to hope that my research is informing something that people can employ on a daily basis that can make their lives healthier.”
Published on May 15, 2013