So some doctors say they were surprised by new research showing that breast cancer patients with dense breasts were no more likely to die than other patients in the study.
Yet women with less dense breasts were more likely to die of their breast cancers if they also were obese, according to the study, involving more than 9,000 women, in today’s Journal of the National Cancer Institute.
“It’s a bit of a surprise,” says Barbara Monsees, chairwoman of the American College of Radiology‘s breast imaging commission, who wasn’t involved in the new study. “It shows we have a lot to learn about dense breast tissue and its implications for screening, diagnosis and treatment.”
The findings should be reassuring to women with dense breasts, whether they are healthy or being treated for cancer, says study co-author Karla Kerlikowske, a professor of medicine at the University of California-San Francisco. “Treatments are really good now,” Kerlikowske says. “Our density isn’t going to affect how we do. It doesn’t put us at additional risk of dying.”
Kerlikowske notes that other factors can increase a woman’s risk for developing cancer, but not necessarily for dying from the disease. For example, women with a strong family history of breast cancer may be more likely than other women to get cancer, but not more likely than other patients to die.
American College of Radiology via AP
It can be harder for a mammogram to spot a possible tumor in a dense breast, left. Dense tissue and potentially cancerous spots appear white on X-rays.
While many women have areas of dense tissue in their breasts, only about 25% are considered to have dense breasts, with at least half the breast composed of dense glandular and connective tissue, says study co-author Gretchen Gierach, a scientist at the National Cancer Institute. In general, dense breasts are more common in younger women.
Dense breasts can make mammograms harder to interpret, says Patricia Ganz, a professor at the UCLA School of Medicine. While fat appears black on mammogram films, both tumors and dense breast tissue appear white. So radiologists looking for tumors — trying to pick white spots out of a mostly white field — may not find them. Radiologists have an easier time picking out tumors in fatty breasts.
Breast density has recently become a political issue.
In the past three years, four states — Connecticut, Texas, Virginia and New York— have passed laws requiring that women be notified if their mammograms indicate that they have dense breasts. Critics say the letters that women receive don’t necessarily explain what women should do with that information.
Breast cancer survivor JoAnn Pushkin successfully lobbied for New York’s law, which will take effect in January. Pushkin, 52, was diagnosed with an advanced tumor in 2005, she says, because her annual mammograms missed the cancer. Pushkin says all women with dense breasts should be informed of mammography’s limitations, so that they can consider additional tests, such as ultrasounds.
Yet Monsees says the law, while well-intentioned, may be premature.
Studies of ultrasounds have focused on women at very high risk of breast cancer, not the general population. Even then, ultrasounds found only a few more cancers than mammograms alone, Monsees says. Yet giving ultrasounds to everyone dramatically increases the cost of screening, the number of “callbacks” that trigger repeat imaging, as well as unnecessary biopsies, which cause additional pain and anxiety, Monsees says.
And Kerlikowske notes that the issue of breast density is far more complicated than some advocates suggest. Radiologists often disagree, for example, so that one may categorize a woman’s breasts as dense while another may not. And the significance of breast density changes greatly depending on factors such as a woman’s age. Because breasts normally because less dense as women age, a 60-year-old whose breasts remain very dense could be at much higher risk of cancer than a 40-year-old with equally dense tissue, Kerlikowske says.
“What we want to do is save lives from breast cancer,” Monsees says. “Whether we can do that with additional screenings is unknown.”
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