On the heels on NY State’s Breast Density Notification Law, which mandates that women with dense breasts be told they may be at increased risk for breast cancer, comes the reassuring news that having increased breast density does NOT increase the risks of dying from breast cancer.
In order to determine if higher mammographic breast density is linked to a reduced survival in breast cancer patients, Gretchen L. Gierach, Ph.D., M.P.H., of the Division of Cancer Epidemiology and Genetics (DCEG) at the National Cancer Institute in Maryland, and colleagues looked at data from the U.S. Breast Cancer Surveillance Consortium and examined 9,232 women who were diagnosed with primary invasive breast carcinoma between 1996–2005 with an average follow-up of 6.6 years. The researchers studied the relationships between mammographic breast density and risk of death from breast cancer and all causes. Mammographic density was measured using the Breast Imaging Reporting and Data System (BI-RADS) density classification.
The researchers found that density does not influence the risk of death once the disease has developed. They write, “It is reassuring that elevated breast density, a prevalent and strong breast cancer risk factor, was not associated with risk of breast cancer death or death from any cause in this large, prospective study.”
Studies such as these are point out that the most important factor in breast cancer survival is the behavior of the the tumor itself, and not necessarily the risk factors that led to development of cancer in the first place. The analogy I like to use is that of traffic density and accident mortality. The chance of your being in a car accident is of course increased as population and number of drivers, automobiles and passengers in them increases. But your chance of dying in an individual car accident is related more to the circumstances of that accident – the drivers involved, the speed, the road conditions that day, etc – than to the fact that the accident occurred.
One more argument against mandatory breast density notification laws
Presuming that the woman in this study had their mammograms done long before any state passed a breast density law, this study further begs the question as to what benefit these laws will have for women, especially those under age 50, most of whom have dense breasts. (See my previous post on why these laws are misguided.)
At this point, breast density laws are simply legislation based on uncertain science advocated for by women desperate to eradicate breast cancer deaths and passed by legislators who refuse to accept the uncertain state of medical science.
In my opinion, it would be better to focus our legislative efforts on funding research in to the possible environmental causes of breast cancer, and on reducing the levels of known carcinogens in our environment.
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CBS News does a great job reporting on this issue
