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

MOST RECENT POST ON THIS ISSUE  Dense Breasts on Mammogram. No need to be Afraid.

Once again, legislators are meddling into healthcare. This time, it’s in my own home state, where Governor Cuomo has just signed a bill requiring radiologists to notify women when their normal mammogram also shows that they have dense breasts. In such cases, the following text must be included in the lay summary mammogram report given to the patient –

“Your mammogram shows that your breast tissue is dense. Dense breast tissue is very common and is not abnormal. However, dense breast tissue can make it harder to find cancer on a mammogram and may also be associated with an increased risk of breast cancer.

This information about the result of your mammogram is given to you to raise your awareness. Use this information to talk to your doctor about your own risks for breast cancer. At that time, ask your doctor if more screening tests might be useful, based on your risk. A report of your results was sent to your physician.”

New York is the fifth state to pass a mandatory breast density notification law. As of this writing, Connecticut, Virginia, California and Texas have similar laws.

What is Breast Density ? 

Breast density is a subjective radiologic assessment of how well x-rays pass through the breast tissue. It is a surrogate for how much of the breast is composed of glandular tissue and how much is fat. The radiologist reading the mammogram classifies the breast composition as one of the following  –

1. Almost entirely fat (<25% glandular)
2. Scattered fibroglandular densities (25-50%)
3. Heterogeneously dense breast tissue (51-75% glandular)
4. Extremely dense (> 75% glandular)

For the purposes of the law, dense breasts are defined as those that are heterogeneously dense or extremely dense.

Mammographically dense breasts are extremely common, especially in younger women. According to a recent report of mammograms here in New York City, 74% of women in their 40s, 57% of women in their 50’s, 44% of women in their 60’s and 36% of women in their 70’s had dense breasts.

What We Know (and Don’t Know) About Breast Density

Increased breast density can be a risk factor for breast cancer . 

The mechanism is unknown, but it may be that breast density is just the end result of other factors that increase breast cell proliferation and activity – factors like genetics and postmenopausal hormone use.

How much of a risk? Well, it depends on what study you read and who you compare to whom. If you compare the two extremes of breast density in older women, those with extremely dense breasts have a three to five-fold higher cancer risk than those with mostly fatty breast. The risk is lower than that in those in the middle category of breast density and in younger women, though not well-defined.

The truth is, we really have no way to translate individual breast density into individual risk. Researchers are trying to see if breast density can be incorporated into current risks assessments such as the Gail Model, but at this point, breast density has not been shown to add much more than we already know about a woman’s risk from using these models.

Dense breasts can obscure a cancer on mammogram.  

This makes mammogram less reliable in women with dense breasts. Digital mammograms may be better at finding breast cancers in women with dense breasts who are also peri-menopausal or < age 50, but it is not known if this translates into better outcomes.

Additional testing with ultrasound and MRI can find cancers that mammograms miss in women with dense breasts. Unfortunately, breast ultrasound and MRI screening tests are less specific than mammograms – three times as many biopsies will be done, most of which will not be cancer.

We do not know if additional screening beyond mammograms saves lives.

It might seem to makes sense that it would, but there are no randomized trials to show this. For now, this additional screening is only recommended in women at highest risk for breast cancer based on other factors such as genetic, family and personal health history.

Why the Breast Density Law is Misguided

Our legislators have women’s best interests at heart, but unfortunately, when it comes to the practice of medicine, they really don’t know what they are doing. Allow me to explain…

1.Most women under age 60 have dense breasts.  

Three quarters of New York women in their 40’s, all of whom have just had a normal mammogram, will now be told that they may be at increased risk for breast cancer.

2. Breast density measurement is subjective. Different radiologists may give the same mammogram different ratings. Use of computerized density measurement could alleviate inter-observer variability, but there is not yet a standardized computer rating system.

3. Breast density can vary across a woman’s menstrual cycle and over her own lifetime. The same women being scanned at a different time of month or at a later year can land into a higher or lower breast density category, and may or may not get that letter above. Recent research suggests that a single breast density reading may not be the best way to predict breast cancer risk, and that the risk may be confined to those women whose breast density does not decrease with age.

4. Sonogram and/or MRI for breast cancer screening is currently not recommended based on breast density alone. Additional screening beyond mammography is only used in women at highest risk for breast cancer  – those with cancer in a first degree relative with a high risk gene mutation, a family history suggesting one of these mutations, a Gail model or other combined lifetime breast cancer risk assessment >25% or a history of chest irradiation. Even in this group, declines in morality with the additional screening have not yet been shown, and the false positive rate of this additional testing is extremely high – only 20% of abnormals are cancer  when biopsied.

There are no recommendations to use sonogram and MRI in otherwise low risk women, and none that have shown that using it based on breast density alone saves lives.

5. Additional screening adds significant costs to breast cancer screening.  For some women, this additional cost may not be covered by insurance. While Connecticut has passed a law mandating that insurers cover additional sonograms, New York State has not.

6. The law is a medico-legal nightmare.  The legislators are creating a medical standard where there is none. That however, has never stopped the lawyers.

I would expect a lot more business for radiologists doing defensive breast ultrasounds ordered by referring docs who don’t want to get sued for a missed diagnosis by a woman with dense breasts. After the first breast density law passed in Connecticut, the use of ultrasound in that state skyrocketed.  (The American College of Radiology, by the way, urges caution on breast density legislation.)

I would also expect a lot more lawsuits for missed diagnosis aimed at the referring physicians whenever dense breasts are noted on a mammogram, even if that woman had no other risks factors for breast cancer.

7. The EMR Makes This Law Unnecessary. As EMR use expands, women will be able to read their actual radiology report online. Those who want to know their density will, and the rest will not be unnecessarily alarmed.

8. The law violates the free speech of physicians. This regulation did not originate from within the medical community or the department of health. It is a lay attempt to push screening beyond what the evidence supports at this point in time, and to set a medical standard (ultrasound for every woman with dense breasts) that does not exist.

At This Point, What Can be Done?  

Short of radiologists filing a lawsuit claiming free speech violation ? (Not a bad idea I think…)

We have 180 days before the law takes effect. In that interval, I would recommend that the New York State Health department come up with some educational materials on breast density that informs rather than frightens women. They could include information about breast cancer, mammograms in general, their limitations, benefits and harms. And tell women what to do and where to go if they feel a lump or have a breast symptom.  This additional material can be included with the report so that women actually get the information they need about breast cancer screening, rather than an unexpected scare when what they thought they had just gotten was a normal mammogram.

Hmmm, that’s actually not a bad idea…If someone wants to pass a law that Department of Health written breast cancer screening info be given out at the time of Mammography, I’d get behind it in a second.

But telling the majority of women in their 40’s who have just had a normal mammogram that they may be at increased risk for breast cancer? That’s just wrong.