Good News About Breast Cancer Rates in Marin County

For almost 20 years, concern about elevated breast cancer rates in Marin County compared to California, the country, even the world, has been part of the fabric of our community. Breast cancer researchers and advocacy groups in both the local and wider community have looked at a combination of factors, including women’s ages, ethnicity, levels of income, family history, childbearing patterns, use of alcohol and the environment, to try to provide some answers.

Now we have received some very good news on the breast cancer front in Marin County. The Cancer Prevention Institute of California recently announced a 31 percent drop in new breast cancer cases in Marin County since 2001. Rates of breast cancer in Marin County have fallen to their lowest levels and are now about average for the state. Deaths from breast cancer here have decreased by 65 percents since 1988.

The study shows that a change in one factor – postmenopausal hormone replacement therapy (HRT) – is likely a strong contributing cause for the drop. When studies first showed a probable link between HRT and breast cancer, fewer than 10% of women in Marin County continued with HRT leading to a sharp decline in the number of breast cancer diagnoses.

These new findings will help reduce our anxiety, but they still cannot give us the one definitive answer we want. What is the one thing we can do to prevent breast cancer in the first place, and if diagnosed, keep it away for good?

All cancers, including breast cancer, are complicated. Cell division and DNA defense mechanisms are not perfect. Plus, risk factors are not the same for everyone. Even family history and the presence of certain genetic mutations are not totally reliable predictors. Women need to educate themselves about their individual risks and then develop a strategy with the help of a physician for managing the risks which will have the greatest impact over a lifetime.

Some of the highest risks, unfortunately, are out of our control:  being female, over age 50, family history, breast density, and a history of breast cancer. Secondary factors include: age at which menses and menopause began; obesity; more than two alcoholic drinks per day; and history of other cancers. Factors that put us in the low risk category; having a first child before age 30, breastfeeding, use of medicines such as Tamoxifen, and exercise.

I urge women to focus on simple strategies for improved breast health.

1. Get a screening mammogram each year. There has been some controversy about when screening mammograms should start, but every professional medical organization continues to recommend annual screening mammograms starting at age 40. Yes, the potential for false positive results and the need for further tests is present, but mammograms are safe and convenient and most importantly, they keep people from dying. Studies show that finding cancers earlier has resulted in a 30-35% decline in breast cancer mortality rate with the use of mammograms.
2. Be aware of your own breast tissue and changes in your breasts. Do not hesitate to see your doctor if any changes occur. 
3. Take steps to modify risk factors you can control.
   • Obesity. Our risk for breast cancer increases if we continue to gain weight over the course of adult lives, especially after menopause. For every one point we go up in the body mass index scale (BMI), our breast cancer risk increases 5%.
   • Alcohol. Drinking wine and other alcoholic beverages is part of the social fabric, perhaps more so here in Marin County. Seventy-six percent of women in this county reported having more than two drinks a day compared to 50% in California overall. Drinking this amount puts you at higher risk, and even higher if you drink more – three drinks/day results in a 50% higher risk; each additional drink increases the risk by 6%.
   • Exercise. Studies have shown that the single most important action women can take to decrease their breast cancer risk is cardiovascular exercise. To get the most benefit, you should keep your heart rate at sustained level of 60% of your own maximum heart rate (220 minus your age) for 150 minutes per week or more.
   • Nutrition: Follow the nutritional guidelines we know are good for optimum health – incorporate lots of whole grains, fruits and vegetables into your diet, and keep your intake of fat, especially saturated fat low. Studies are mixed on whether Vitamin D levels can help manage your risk, but since it is important for bone health, I recommend supplements to my patients.