Every October, our 200+ grantees from all over the world come together to take part in a conversation about the current landscape of breast cancer research during our annual Symposium and Awards Luncheon.
This year's topic, "Breast Cancer: Prevention is the Best Cure," included a panel and Q&A session featuring Dr. Graham Colditz, an authority on the effects of lifestyle factors on future breast cancer risk; Dr. Andrew Dannenberg, an endocrinologist by training who is studying how obesity causes a chronic inflammatory condition in the breast and promotes breast cancer; Dr. Susan Domchek, whose research is focused on understanding genetic risks and prevention; and Dr.Peter Greenwald, this year’s Jill Rose awardee for outstanding research excellence in recognition of his contributions to cancer prevention research and policy.
Scientific Director Larry Norton and Chairman of the Scientific Advisory Board Clifford Hudis moderated the discussion, which covered topics including genetic risk and screening, diet and exercise, chemoprevention and reducing the risk of breast cancer recurrence.
Dr. Norton began by explaining that most cancers are not caused by gene mutations passed down through families. Instead, they are sporadic, a result of a lifetime of exposures to everyday assaults on our DNA. Because cancers typically occur later in life, there are many opportunities for preventive intervention. Even those with inherited gene mutations may be able modify their risk with lifestyle changes, drugs or surgery.
Scientists currently understand a lot about what causes cancer, but don’t yet understand enough about how or why one person will get cancer while another will not. Learning more about prevention is key and will be different for each individual.
Dr. Greenwald emphasized that while the ultimate goal of prevention is to have a lifetime effect—that is, prevent breast cancer from ever occurring—it’s important to realize that prevention may just be a delay in diagnosis. But delaying breast cancer by years or even decades isn’t trivial, he said.
Obesity and Breast Cancer
The conversation turned to obesity and what it means for breast cancer diagnoses. Poor nutrition and unhealthy eating habits have led to an obesity epidemic in the U.S. and a growing obesity problem in developing countries as they adopt more westernized lifestyles. Obesity is known to increase the risk of breast cancer after menopause and increases the risk of recurrences and at any age. In fact, the American Society of Clinical Oncology recently released new recommendations to help oncologists advise their patients on reaching and maintaining a healthy weight after a breast cancer diagnosis. Now, research is uncovering the mechanism behind this relationship.
More than 50 percent of cancers could be prevented with what we already know about the effects of diet and exercise, Dr. Colditz stated. His work has shown that diet and exercise can impact a woman’s future risk of breast cancer.
Additionally, work by Drs. Dannenberg and Hudis has shown that obesity leads to chronic inflammation in the breast that promotes tumor growth. Unlike inflammation that happens after a physical injury, inflammation caused by obesity doesn’t go away. They explained that when fat cells die, they attract immune cells that release inflammatory molecules. These molecules fuel tumor growth.
The doctors found this type of persistent inflammation in 90 percent of their obese subjects and in one-third of healthy-weight women, suggesting they may have an increased risk of breast cancer.
They are now developing a blood-based test to detect inflammation and identify otherwise healthy women who may be at risk.
Breast cancer screening is an ongoing debate, both in high-risk women (those with a strong family history) and normal risk women (the general population). While most breast cancers are not caused by inherited mutations, there is a heightened awareness of genetic risks and concerns about who should undergo genetic screening and when.
While some studies suggest that genetic screening based on a family history may miss people carrying deleterious genetic mutations, more studies are needed before recommending widespread genetic screening in the general population.
Research by Dr. Domchek and other BCRF grantees is helping us understand the impact of genetic mutations and has uncovered other genetic events that modify these risks. For instance, Drs.Kenneth Offit,Fergus Couch and others have shown that certain combinations of rare genetic modifications that occur with more common mutations in the BRCA genes can modify the risk of breast or ovarian cancer. As we learn more about how these combinations influence risk, doctors will be able to better advise their patients on prevention measures and better treatments can be developed for BRCA-related cancers.
The overarching theme from the symposium was that research and education are key to achieving real prevention. We know that cancer risk is a complex mixture of environmental and genetic factors that are unique to each individual and that the right preventive strategy will need to take into account individual risk. Research has advanced our understanding of risk assessment and is leading the way to more individualized preventive strategies.