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Discovering the causes of cancer and the means of prevention

Gretchen Gierach Awarded Scientific Tenure by the NIH

Gretchen Gierach

In April 2017, Gretchen Gierach, Ph.D., M.P.H., was awarded scientific tenure by the NIH and promoted to senior investigator in the Metabolic Epidemiology Branch. Dr. Gierach has developed an interdisciplinary breast cancer research program with a special emphasis on the epidemiology of breast density, one of the strongest risk factors for breast cancer. Her work employs a range of technologies and approaches to improve the measurement of density, delineate risk factors for elevated density, and understand mechanisms that mediate its relationship to breast cancer risk.

Dr. Gierach is principal investigator of the Breast Radiology Evaluation and Study of Tissues (BREAST) Stamp Project, a complex field effort designed to characterize the radiologic, histologic, and molecular features of dense breast tissue. Most analyses of mammographic breast density (MBD) have employed subjective visual categorizations or computer-assisted quantification of two-dimensional images (area density), which ignore breast thickness. Dr. Gierach incorporated cutting edge methods to measure MBD in three dimensions, as a volume, a novel component of the project.

As a separate yet complementary effort to her MBD research, Dr. Gierach leads several projects to better understand the role of hormones as etiologic factors in breast cancer. Her key work has demonstrated that estrogen metabolite profiles contain important risk information and non-sex hormones, such as insulin-like growth factors (IGFs), may influence molecular markers of risk. She is also evaluating the interrelationships between endogenous hormones, involution of terminal duct lobular units (TDLU), and MBD. TDLUs are milk-secreting structures thought to be the tissue of origin for the majority of breast cancers.  

In a recent study within Kaiser Permanente Northwest and Colorado, Dr. Gierach and colleagues observed tamoxifen treatment reduces risk of contralateral breast cancer in a general community health care setting, an important confirmation of clinical trial results. They also reported on changes in MBD after initiation of treatment: patients who experienced large reductions in MBD following tamoxifen had an improved prognosis. The finding suggests reduction in MBD as an early indicator of tamoxifen effectiveness and could have value for clinicians and patients when deciding whether to continue tamoxifen therapy or change clinical management.

Dr. Gierach also completed the field effort of the Ultrasound Study of Tamoxifen, in which she and colleagues used novel ultrasound tomography methods to assess changes in volumetric breast density within the first year of tamoxifen therapy. This technology may provide a safer alternative to mammography for monitoring therapy-induced changes in MBD because it allows repeated measurements without exposing women to ionizing radiation.