Density Matters

[dee]

January 18, 2007



Cancers are more likely in dense breasts, study shows


Connection goes beyond masking effect, researchers say
JEFF DONN
The Associated Press


BOSTON - Cancer turns up five times more often in women with extremely dense breasts than in those with the most fatty tissue, a study shows, signaling the importance of a risk factor rarely discussed with patients.

On mammograms, fat looks dark, but dense tissue is light, like tumors, so it can hide the cancers. But this study confirms that cancers are also more frequent - not just hidden - in women with dense breasts.

That means that density is a true risk factor, along with other strong predictors such as age and the genes BRCA1 and 2. Yet specialists say breast density is rarely considered with other risk factors in discussions between doctors and patients.

"It's been ignored to an absolutely unbelievable degree," said study leader Dr. Norman Boyd at Princess Margaret Hospital in Toronto.

The Canadian study by cancer centers in Toronto and Vancouver focuses on how and when cancers were found over eight years in existing records of 1,112 women collected between 1981 and last year. It is being reported in today's New England Journal of Medicine.

Breast density comes from the presence of more connective, duct-lining and milk-gland tissue than fat. But a woman can't judge her own density; it is routinely evaluated from a mammogram.

Risk factors

Previous studies had linked breast density to a higher rate of cancer, pointing to both masking and a separate biological risk.

In this study, women with at least 75 percent dense breasts showed five times more likelihood of cancer than women with less than 10 percent density.

The researchers went further by calculating just how many more cancers were found at screening, within the next year, and in the years afterward. Cancers found within a year were considered likely to be present, but masked, during the earlier mammogram. But a true biological risk was seen in cancers discovered by mammogram or long afterward.

In this study, cancers were 18 times more likely in women with the densest breasts within the first year after mammograms - the masking effect.

However, cancers in women with the densest breasts were also more than three times more likely to turn up at the time of screening and after the first year following a mammogram. That confirms and helps quantify the true biological link between density and cancer.

"I think the masking thing is important, and it does happen, but the most important thing is that this is an incredible risk factor," said Dr. Karla Kerlikowske, of the Veterans Affairs Medical Center in San Francisco, who wrote an accompanying editorial. "This probably counts for a large percentage of the cancer that's occurring."

[caya]

Thanks for posting this important article Dee. I had my mastectomy at Princess Margaret Hospital in Dec. 2006 - ( known by the locals as PMH) - w world class hospital on the cutting edge of research and clinical trials.


This article was all over the local news here in Toronto yesterday - I could be the poster girl for this article. This version of the article is missing the important section that says : "Since dense tissue can mask tumours, the study authors suggest alternate imaging techniques such as digital mammography, ultrasonography, and MRI, be evaluted for women with extensive breast density." I mention this because I just had a regular mammo and breast ultrasound in June 2006, ( all clear supposedly), then had a breast reduction in Oct. 2006 - my plastic surgeon found my 1.7 cm tumor - subsequent mastectomy in Dec. 2006 - starting chemo next week.

We have to be vigilant in advocating for breast MRIs for dense breast tissue gals. I know I am going to be.

[Hopeful]

I, too am in this club. I was never counseled about breast density. I had no idea until after my dx, when I went to the mammography center to get all my prior reports. I read that density was an issue for me in a report that was six years old!!!. Not one doctor had ever mentioned it. I would have insisted on much more rigorous screening. In point of fact, I am much more concerned about developing a new primary cancer than having a recurrence of the original one.

Hopeful

[dee]

It was noticing and remembering that my mammogram results had mentioned dense breasts the year before cancer arrived (less than a year, actually, about 10 months) that piqued my interest in this article. No one even mentioned it to me back then, I just happen to retain details that seem odd to me, which that term did. Now, this article would seem to indicate I should have received counsel, which, of course, I didn't. Other literature I have read has indicated premenopausal women tend to have denser breasts, so I figured it was just an indication of my youthful stature, not a red light for potential bad news down the road...