With the high incidence of breast cancer in Marin County and in honor of national Breast Cancer Awareness Month we’ve compiled a list of statistics and facts from the Northern California Cancer Center, the American Cancer Society and the Department of Health and Human Services in Marin to shine a spotlight on and clear up myths about the disease. —S.F.
What is the chance you will be diagnosed with breast cancer?
According to the National Cancer Institute, about 1 in 8 women (13.2 percent) will be diagnosed with breast cancer during their lifetime. By age at diagnosis, this averages to:
From age 30 through age 39: 1 in 229
From age 40 through age 49: 1 in 68
From age 50 through age 59: 1 in 37
From age 60 through age 69: 1 in 26
The Facts About Breast Cancer in Marin County
Why are there higher rates of breast cancer in Marin than in other parts of the United States? For a five year period up to 2003, breast cancer rates in Marin were 17 percent higher than the rest of the nation, according to Rochelle Ereman, director of community epidemiology at the county health department. Why Marin? Although there are a number of possibilities, Ereman points out that there are more women in Marin with known risk factors for breast cancer such as using certain types of hormone therapy, daily alcohol consumption and childbearing patterns (having fewer children later in life). This would cause Marin’s rates to be higher than other areas, because it would put more women at an increased risk for breast cancer. Ereman says these factors account for much of the rate difference seen in Marin but there is still uncertainty if they account for the entire excess rate. 
But there is good news! According to the Department of Health and Human Services, updated estimates show that mortality rates in Marin and California have declined in the past decade, meaning fewer women are dying of breast cancer.
“In 2002 there was a lot of media attention surrounding hormone replacement therapy (HRT) and the link to breast cancer. With fewer women using HRT, we’ve started to see breast cancer rates coming down substantially,” says Tina Clarke, Northern California Cancer Center research scientist and Stanford University consulting assistant professor.
How many women in Marin are diagnosed? According to the most recent data from the Northern California Cancer Center, for the period between 2000 and 2004,1,248 women were diagnosed with invasive breast cancer, meaning the tumor had started to invade the surrounding tissue. 261 women were diagnosed with noninvasive breast cancer, meaning tumor cells were detected but had not spread.
