Karen Garloch

Mammography isn’t always accurate at diagnosing cancer in women with dense breast tissue

In last Sunday’s Observer, I told the story of UNC Charlotte cancer researcher Pinku Mukherjee, who has developed a blood test that can help detect breast cancer in women with dense breast tissue, whose mammograms are not always accurate.

Mukherjee became interested in applying her research to this problem when she learned these startling statistics: Overall, about 25 percent of tumors are missed by mammograms. But for women with dense breasts, the rate is 50 percent.

Women with dense breasts can have cancer that goes undetected by mammograms for years before they are suddenly diagnosed with late stage disease. That’s because dense tissue shows up white on a mammogram, just like cancer.

Making matters worse, even though 40 percent of women have dense breasts, they’re not always aware of it.

Nancy Cappello, founder of a nonprofit group called Are You Dense, was one of them.

The Connecticut woman learned she had late-stage breast cancer in 2003 after having “squeaky clean” mammograms for 11 previous years. Six weeks after the 11th “normal” mammogram, her cancer was discovered when her gynecologist felt a thickening in her right breast. Subsequent testing showed the cancer had spread to 13 lymph nodes.

Cappello later lobbied her state legislature to pass a law requiring doctors to inform patients when a mammogram reveals they have dense breast tissue. Twenty-four states have such laws, including North Carolina.

Since 2009, Mukherjee has developed a blood test that can distinguish between malignant and healthy breast cells. The test, produced by her startup company OncoTab, wouldn’t actually diagnose breast cancer, and it’s not a replacement for mammograms. But it is an inexpensive adjunct to mammography, especially for women with dense breasts, she said.

The OncoTab test will be available to patients with a doctor’s prescription for about $150 in February at www.oncotab.com/.

Like blood tests for cholesterol, the OncoTab test will provide a range of what’s normal. Women with dense breasts could use it to monitor their levels of an abnormal protein associated with breast cancer. Those outside the normal range, or whose levels increase over time, could go on to have more expensive and definitive procedures, such as ultrasounds or MRI scans.

There’s another option for women with dense breasts. Dr. Deborah Agisim, a mammography specialist at Charlotte Radiology, recommends they get 3-D mammography instead of conventional mammograms.

Since 2013, both Charlotte Radiology and Mecklenburg Radiology Associates have offered this test. From the patient point of view, it’s no different because it uses conventional mammography technology and includes two-dimensional images. Additional 3-D images are taken, offering more views of the breast.

“It’s like turning the breast into a layer cake, and you’re able to look at thin slices of tissue,” Agisim said. “That has reduced the ability of the cancer to hide.”

Since using 3-D mammography, Charlotte Radiology has recalled 35 percent fewer patients. That means fewer false positives and fewer women called back unnecessarily for follow-up testing.

And even with fewer callbacks, doctors have found more invasive cancers, Agisim said.

Most insurance plans cover conventional mammograms but not 3-D views. Both Charlotte Radiology and Mecklenburg Radiology charge an extra $55 for 3-D mammography.

Karen Garloch: 704-358-5078, @kgarloch