SACRAMENTO, Calif. -- It took seven years of annual mammograms and a cancer diagnosis for Amy Colton to learn something her doctors had realized from the beginning: Her breast tissue is so dense that it could have masked tumors on earlier exams.
"I requested a copy of the report sent from my radiologist to my primary care physician, and every single one said, `Patient has extremely dense breast tissue,'" the registered labor and delivery nurse said. "I was really outraged that I didn't know this."
About 40 percent of women over 40 have breast tissue dense enough to mask or mimic cancers on mammograms, but many of them don't know it. Mammogram providers in California will be required to notify those patients, and suggest that they discuss additional screenings with their doctors based on their individual risk factors, if Gov. Jerry Brown signs a bill that the Legislature passed this month. Similar laws have passed in Texas and Connecticut in the past two years but no data is available yet from either state on the effect of the legislation.
"The notice in the bill is a two-sentence notice that gets added to a letter," said the bill's author, Democratic state Sen. Joe Simitian of Palo Alto. "I believe these two sentences can save thousands of lives."
Brown has not given his opinion about the bill, but many doctors oppose it. Researchers studying breast density, a relatively young field, said such requirements may end up causing undo anxiety in millions of women and lead to unnecessary and expensive ultrasound or MRI screenings.
The California Medical Association, which represents 35,000 doctors, recommended a public education campaign instead of individual notifications, and said there isn't enough evidence to support the idea the extra money spent on additional screenings will save more lives.
Those tests could cost the state more than $1 billion, and many women wouldn't be able to afford them, said Dr. Karen Lindfors, a professor of radiology and chief of breast imaging at the University of California, Davis Medical Center in Sacramento. She testified against the bill before a legislative committee.
"I just don't think that at this point we have the ability to meet the kind of demand either financially or in terms of manpower that this is going to create, and we also don't have proof that it's going to save lives," she said.
The women who would receive the notifications have more tissue than fat in their breasts. As women age, their breasts become more fatty. Fat appears black on a mammogram, making it easier to spot cancer, which shows up as white.
Doctors agree that high breast density is an increased risk factor for cancer, but researchers say the issue needs more study to determine whether the risk is great enough to justify a higher level of screenings for women who have it.
Pre-menopausal women are more likely to have dense tissue, regardless of whether they are at high risk for breast cancer, said Celine Vachon, an associate professor of epidemiology at the Mayo Clinic in Rochester, Minn. She said women who get the notifications required by the California bill could be frightened into seeking additional screenings, such as MRIs or ultrasounds, which can pick up false positives and cost thousands of dollars.
"If women want their breast density information, that's their right," Vachon said. "However, breast density is not yet a risk factor that's used clinically, so what women will do with this information is not clear. We need improved density measurements as well as models that do a better job of predicting women's risk. Everyone wants density to be this silver bullet, but to date, it's not."
Colton, who got the California legislation rolling by contacting Simitian's office, said women ought to be told whether their breast density could make cancer difficult to detect.
She said she practiced self-exams monthly, had no family history of breast cancer and thought she was among the lucky cohort of women at a low risk for breast cancer. But five surgeries, six weeks of daily radiation and 15 rounds of chemotherapy later, she is angered that she went years without being told about her dense breast tissue.
"I don't want anyone to think this is a rare story. There are countless women like me, and many with worse diagnoses," she said.
Dr. Judy Dean, a diagnostic radiologist in Santa Barbara who specializes in breast imaging, supports the effort. She said 20 of her patients have found cancers through ultrasounds after she informed them that their dense tissue might be hiding tumors in a mammogram.
"Negative doesn't mean negative; you could still be positive," she said.
All radiologists agree that a mammogram – an X-ray image of the breast – is the best way for a woman to discover whether she has dense tissue, but few agree on how to proceed with that information.
Researchers have been experimenting with new breast imaging techniques that might provide the same answers as an MRI or ultrasound for women with a high risk for cancer, but with less expense. 3-D X-ray images known as "stereo mammograms" and molecular breast imaging are two techniques that are better than traditional mammograms at spotting cancers and cost much less than MRIs.
Some say a notice about the hidden risks of dense tissue should be sent to all women receiving the results of their mammogram, not just those with dense tissue. That way, everyone can be armed with the available information, said California state Assemblywoman Linda Halderman, a former breast cancer surgeon.
She said the bill would end up giving women with low breast tissue density false assurances they are not at risk for cancer.
"We're offering something to women that doesn't help improve their care or shed any light on the best way to assess their risk for breast cancer," said Halderman, a Republican from Fresno. "Unfortunately, breast density is just one of those things we don't know about yet."