NOVATO -- Vitamin D may provide a clue in determining why Marin County women are afflicted with one of the highest breast cancer rates in the nation, a preliminary study headed by a Marin scientist indicates.
The new study involving a small sample of Marin women suggests a genetic trait involving a receptor that activates vitamin D may be a factor.
The Journal of the American College of Surgeons reported that UC San Francisco surgeon scientist Dr. Kathie Dalessandri of Point Reyes Station and colleagues, including investigators at InterGenetics Inc. of Oklahoma, discovered that cells from 338 Marin women reflect variations associated with breast cancer risk.
Dalessandri noted the findings, based on a review of frozen samples of high-risk women involved in a previous Marin study, must be confirmed in a much larger study before conclusions can be drawn.
But based on the small sample, "We found that women who were at high risk for breast cancer were 1.9 times more likely to have a specific vitamin D receptor variation than the general population," she added.
Dalessandri had no advice on what, if any, level of vitamin D could help combat breast cancer.
The Marin County Department of Health and Human Services oversees a pioneering, ongoing breast cancer study -- www.marinwomensstudy.org -- that indicates there is no link between the disease and the amount of time spent in the county. Cell samples from that study were examined by researchers in the analysis involving vitamin D, using risk-rating technology developed by Eldon Jupe of InterGenetics.
"If genetic variations in the vitamin D receptor prove to be causally linked to breast cancer, that may help pave the way for new ways to prevent or treat the disease through vitamin D supplementation -- though any such approaches would have to prove safe and effective in clinical trials, which can take years to reveal impact," a report said.
Researchers already have a trove of information collected in connection with the county's ongoing Marin Women's Study, which established a database focusing on health and risk factor data, genetic variables, hormone levels and mammographic breast density measurements of 14,000 Marin women.
The exhaustive probe, launched after Marin logged one of the highest breast cancer rates in the nation, involves an analysis by a consortium including county health staff, the Buck Institute for Age Research, the Northern California Cancer Center, Zero Breast Cancer and others. Data includes saliva samples from 8,500 Marin women that allows hormone study as well as genetic analysis of DNA.
, along with review of health histories, childbirth and breast-feeding data, environmental and personal risk factors.
Intense interest in the study was spurred after a National Cancer Institute study indicated Marin's 1998-2002 rate of cancer in non-Hispanic white women was 175 cases per 100,000. At the time, the rate was 7 percent higher than the rest of the Bay Area, 9 percent higher than Los Angeles and 18 percent higher than the nation. Marin posted a rate in 2009 of 147 cases per 100,000 women -- higher that the state's rate of 139.