My research focuses on two main areas: 1) Understanding the genetics and epidemiology of mammographic density and its utility as a risk factor and surrogate marker of breast cancer risk and recurrence and 2) Genetic epidemiology of multiple myeloma, its precursor, monoclonal gammopothies of underdetermined significance (MGUS), and other hemataologic malignancies.
Research by our team in the area of mammographic density has confirmed its importance as a breast cancer risk factor years prior to cancer development; demonstrated that density assessed from both mammogram views and sides result in the same risk estimates and can be used in risk prediction; shown that mammographic density appears a general marker (as opposed to regional marker) of breast cancer risk; described its correlation with other breast cancer risk factors, including diet, anthropometrics and physical activity in adolescence and adulthood; and identified the first evidence for a putative genomic locus housing genes for the trait using linkage studies.
We are extending our initial genetic studies of mammographic density to multiple study populations to identify possible genetic variation that influences this trait. Also, we are conducting a study of over 600 women to examine whether aromatase inhibitors, a widely prescribed endocrine treatment for ER+ breast tumors, influence mammographic density. If so, mammographic density may possibly be used as a surrogate marker to assess response to this type of therapy.
Although mammographic density is a strong risk factor for breast cancer, the mechanism by which it influences breast cancer is unknown. Having established a cohort of 20,000 women with screening mammograms at the Mayo Clinic, we are following these women for new breast cancer and will continue investigations to better understand the density and cancer association. Using our cohort, we are currently examining whether mammographic density is a risk factor for all breast cancers or only those of specific subtypes (i.e. ER+ vs. ER-; basal vs. luminal subtypes; high vs. low grade, etc.). We are collaborating with investigators and cohorts at two other sites, UCSF and Harvard, to accomplish this goal. This information could better inform risk prediction models for breast cancer.
Another research effort by our team involves identifying genetic risk factors for multiple myeloma (a cancer of the plasma cells) or its precursor, monoclonal gammopothy of undetermined significance (known as MGUS). We recently demonstrated that 1st degree relatives of those with MGUS or MM have a two-fold greater prevalence of MGUS compared to the general population. We are interested in identifying genes that are responsible for increasing ones risk of myeloma and MGUS. An ongoing effort is our collaborative genome wide association study (GWAS) to identify and confirm potential genetic variation (single nucleotide polymorphisms or SNPs) associated with myeloma in conjunction with investigators from Washington University, University of Minnesota and the UK. We plan to examine whether SNPs found to be associated with myeloma are also associated with MGUS, using a case-control study of MGUS, established at the Mayo Clinic. Understanding genes important to myeloma and MGUS will help us to better understand the biology of myeloma and possibly allow for future prevention and treatment efforts.
Another large research effort by our team involves studying whether monoclonal gammopothy of undetermined significance (MGUS), a potential precursor to myeloma, clusters in families of patients diagnosed with MGUS or myeloma.