Pamela Goodwin, MD :: Profile

Marvelle Koffler Chair in Breast Research
Professor of Medicine, University of Toronto
Mount Sinai Hospital, Toronto, Ontario, Canada

Q. Tell us about yourself as a researcher and how you became interested in breast cancer.

A. I combine research with seeing patients, and have done so for over 20 years. Breast cancer affects a lot of women in North America. When I started, there was enormous potential to improve outcomes - so little research had been done. I realized I could make a contribution.

Breast cancer is a complex set of diseases: there is a combination of factors that act together in each case. Early on, I became interested in what we call "patient-related factors" and their impact on breast cancer outcomes. When I started, there was a focus on diet, and in particular dietary fat. We've learned that what has proven important are obesity and insulin levels. Our research has identified insulin as an important factor linking breast cancer outcomes and obesity. Obese women in general have higher insulin levels. Exercise fits in to the equation with breast cancer because it helps to reduce both obesity and insulin levels.

Q. Did you ever seriously consider another kind of career than that of medicine and scientific research?

A. I've had lots of opportunities to do other things, but I haven't wanted to change what I'm doing. Having said that, research is unpredictable and you have to be in it for the long term. In science you have to know what your strengths are and see where you can make a contribution. I run marathons and maybe what's required for long distance running has helped me stay happily in research for the long haul. The fact that incidence rates for breast cancer have declined and outcomes have improved during my career so far make me happy with the decision I made to pursue a career in breast cancer research.

Q. You mention your research on the relationship between weight, metabolism and nutrition, and how these factors impact breast cancer. How has your focus in this research area helped you understand the disease?

A. Breast cancer doesn't exist in isolation. More so than most cancers, the way that breast cancer evolves depends on what is in the woman's blood and body. In other words, the status of the woman herself influences the risk and the outcome. For example, risk is higher if she has a late menopause or late pregnancies. Her hormonal profile - insulin and other hormones like estrogen and progesterone, vitamin D levels - will affect outcome. Breast cancer is not like lung cancer which tends to have a single cause - smoking. Treating women with breast cancer has made me appreciate more than ever before needing to look at the whole person.

I'm very much a mainstream doctor - I utilize all of the available drug therapies in treating breast cancer - but I take into consideration the woman herself, her physiology, and how that can affect her outcome. With breast cancer you can't just look at the patient factors and you can't just look at the tumor factors. It's not an either/or situation. You have to look at both.

In my research I have focused on breast cancer outcomes more than on prevention. With prevention, it's hard to know what information is reliable. What I believe to be reliable are the following: getting regular mammograms, staying physically active, and for some women, taking raloxifen or tamoxifen under their doctor's supervision. Women need to do what's good for their overall health.

Q. You tracked over 500 Canadian women in a recently publicized study, and found a correlation between low vitamin D levels and poor breast cancer prognosis. What did you learn and what remains to find out?

A. We learned that in breast cancer, vitamin D is linked to outcomes. Now that we've seen this correlation, there are a whole bunch of things I'd like to know. At the top of the list: does changing vitamin D in the body by taking supplements make a difference? I strongly feel that we do not know the answer to that question - just because there's a link with vitamin D levels, it doesn't mean that it's causal; it doesn't mean that changing it with supplements will change the outcome.

I'm beginning a collaborative study with another BCRF researcher - Patti Ganz, MD, who is at UCLA. We will first see whether vitamin D levels are low in women diagnosed with breast cancer today (our earlier patients were diagnosed up to 20 years ago). Then, we will provide women with breast cancer and low vitamin D a set dose of vitamin D supplement to see how much their levels change. It's not clear how much supplementation is needed to raise vitamin D levels.

I'm also interested in how we might be able to regulate insulin in the body. There's an approved drug that's been around in Canada and the United States for decades called metformin. It's used to control type 2 diabetes. If it can lower insulin safely for women with breast cancer, maybe we can improve breast cancer outcomes.

Q. What should the average person do now that we know that low vitamin D levels are implicated in breast cancer?

A. My patients are all asking me about vitamin D. The only thing I tell them is to follow supplementation guidelines currently recommended for bone health and, if they are considering taking large doses, to have their vitamin D levels checked. I can't tell you for sure whether vitamin D supplementation will improve breast cancer outcomes. We don't have the data yet.

There are different vitamin D guidelines for overall health, bone and cardiovascular health. In a northern climate, you tend to produce less vitamin D. I tell my patients that if they are thinking of taking more than 400 - 800 or 1000 IU per day, it's reasonable to get their vitamin D levels checked before doing so. We don't have guidelines for vitamin D supplementation with regard to breast cancer yet. And even when we do, it will probably remain very individualized.

We also don't know what form of supplementation is best for breast cancer prevention: it may be D2 or D3. And we don't know the optimal blood levels. The cancer field is very rigorous in how it evaluates things - it's part of our culture. There's a growing body of research that suggests there's an optimal range of vitamin D in the body, but we must verify that range for breast cancer outcomes.

Q. How close do you think we are to preventing or curing breast cancer?

A. For many women with breast cancer this is an era of optimism. We're curing breast cancer one form at a time. HER2 positive breast cancers and Herceptin are an example of how we have significantly improved outcomes compared to 20 years ago. There's still a lot more work to be done on the molecular science side that will yield targeted therapies.

Q. How has BCRF helped you?

A. BCRF has supported important research in the role of vitamin D. It has also helped us look at long - term outcomes of women with breast cancer. We know that it is not adequate to just treat breast cancer. We need to understand the overall health of our patients and think about overall future health risks of women with breast cancer. Is she overweight? Is she physically active? We know these things are important. With BCRF funding, there is rapid turn around time. Often in research, there's so much time between the idea and funding - one to two years. BCRF promotes very leading edge research with a rapid response, more like one to two months!

Q. What's the biggest challenge in cancer research today?

A. Lack of money for research. It's not the creativity of the scientist that's missing. It's the inadequate funding that prevents us from getting to the answers more quickly.

Q. What advice would you give to young physician-researchers?

You must be passionate, as well as have the patience to allow the results to come. You can't be wedded to an answer. All you can do is pose a question and allow the true answer to come through. It's also important to keep your eye on the future, and understand how what you're thinking about today will fit in five years from now, and mesh with studies that others have already begun.

Read more about Dr. Goodwin's current research projects funded by BCRF.