Dense breasts may obscure mammogram results
By Roni Caryn Rabin, The New York Times – 6/16/2014
The doctors were pleased to inform me, the letter said, that the results of the mammogram were normal. Early detection of cancer is important, a report was sent to my referring physician, I should report any lumps, see my health provider, have a physical.
A sentence in the fourth paragraph grabbed me by the throat. “Your breast tissue is dense.”
In journalism, we call this “burying the lead” — tucking the really significant information far down in the story. I knew that having dense breast tissue makes it hard to read mammograms and may increase the risk of breast cancer. I just never knew I had dense breasts.
I’ve had at least half a dozen mammograms, and each one has come back normal. Now I discover these images have been obscured. Dense tissue shows up white on the scans. So do tumors.
“It’s like looking through a window with snow on it, searching for a drop of milk,” said Dr. Carolyn D. Runowicz, a professor of obstetrics and gynecology at the Herbert Wertheim College of Medicine at Florida International University in Miami.
No wonder mammograms miss half of all breast cancers in women with dense tissue.
About 40 percent of women who have mammograms have dense breast tissue, which means they have more connective and fibrous tissue than usual. Until recently, that information was rarely relayed to women, though it was routinely noted in the radiologist’s medical report to the doctor (as “dense parenchyma” that “lowers the sensitivity of mammography”).
Now women from Hawaii to California, New Jersey to New York, are receiving letters about their breast density because of state legislation championed by Nancy Cappello, a 61-year-old Connecticut woman. Her breast cancer had spread to her lymph nodes by the time it was diagnosed 10 years ago, even though she had had normal mammograms every year.
Her tumor was an inch in size when it finally became palpable, Ms. Cappello said in an interview. Her doctor estimated it had been growing for four or five years, even as Ms. Cappello went faithfully for mammograms and received assurances that she was cancer-free.
No one warned her that dense breast tissue could obscure the radiologist’s view.
Unfortunately, there’s still no clear medical guidance on how women should proceed once they’ve been told they have dense breasts. Some experts even question whether having dense breasts significantly increases breast cancer risk.
The letters mandated by New York law suggest women “use this information to talk to your doctor about your own risks for breast cancer” and ask their doctor “if more screening tests might be useful.” The Connecticut law goes further; women with dense breasts are told to consider an ultrasound or magnetic resonance imaging test.
But the American Congress of Obstetricians and Gynecologists doesn’t recommend using additional screening tests just because a woman has dense breasts. The American College of Radiology acknowledges that other types of scans may detect tumors missed on mammograms, but notes that there are no good data showing that women who add an ultrasound or an M.R.I. to mammography live longer.
I did what the New York letter suggested: I called my doctor. He emailed back right away, saying he was not concerned. The density of my breasts was not news to him.
I called my health plan to see if it would cover an ultrasound. I was pleasantly surprised: It would, though not at the same rate as a mammogram, which is considered preventive care that most health plans must cover in full.
Then I called the radiology center to make an appointment, and learned I could drive over and pick up a CD with my mammography images on it at no charge.
I picked up the disc and popped it in my computer. As soon as the images appeared on screen, I could see what the doctors were talking about: Big white clouds were floating in the middle of each dark half-moon image.
“One thing women shouldn’t do is start to worry that there is something wrong” if she has dense breast tissue, said Dr. Carol Lee, a diagnostic radiologist at Memorial Sloan Kettering.
Although the benefits of routine mammography have been debated for years, many women continue to choose it, and experts say they need not stop just because they have dense breasts.
“Mammograms pick up cancers in women with dense breasts every day,” Dr. Lee said.
For dense breasts, however, a digital mammogram is preferable to film, and a three-dimensional mammogram is even better, Dr. Runowicz said.
But there’s a definite downside, other experts note: Additional scans will pick up other suspicious spots that may require intervention, such as biopsy to rule out cancer, even though most of them will turn out to be harmless. Learn about your risk factors for breast cancer at cancer.gov (breast density is not listed here), and use the online calculator to gauge your risk. A woman’s risk increases with age.
Talk to a trusted physician and consider adding an ultrasound or an M.R.I. scan to your screening if you have dense breasts. An ultrasound is cheaper and less invasive, said Dr. Regina Hooley, an assistant professor of diagnostic radiology at Yale.
Mammograms pick up two to seven cancers per 1,000 women screened, and subsequent ultrasounds pick up another three to four small invasive cancers, Dr. Hooley said. Even though there may not be scientific evidence proving a survival benefit from the additional scans, she said, “these are exactly the cancers we want screening to detect.”
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