When a mammogram detects breast cancer in a woman age 75 or older, it’s more likely to be early stage disease that can be treated less aggressively, according to a study drawn from thousands of patients in a Seattle cancer registry.
Dr. Henry Kaplan of the Swedish Cancer Institute and Judith Malmgren, an epidemiologist from the University of Washington’s School of Public Health who has long worked with Kaplan, published the study in the journal Radiology on Tuesday.
“If you do mammograms in the older group, you will find a lot of cancer, the cancers will be early or lower stage, and the patients will therefore need less therapy,” Kaplan summarized.
Mammograms, compared to detection by patients or doctors, typically catch tumors at an earlier stage. That’s important, because older women often can’t withstand the chemotherapy treatment used in later-stage cancer, said Malmgren, the study’s lead author.
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“For older women, who have fewer treatment options, you really do want to catch it early,” Malmgren said.
The paper adds a bit of fuel to raging debates in the U.S. and other countries over mammography screening — what age to begin and to stop, how often women should be screened, whether the risks of treatment outweigh benefits, and of course, the cost to the health-care system overall. A recent paper put the cost of mammography screening in the United States in 2010 at $7.8 billion.
Although older women are at higher risk of breast cancer, with higher death rates from the disease, Malmgren noted, the U.S. Preventive Services Task Force, a panel of independent health experts convened by the federal government, does not recommend mammography screening in this age group, saying there is insufficient evidence to weigh risks and benefits.
Not only does most breast-cancer research not include older women, in some regions of the world — the United Kingdom, for example — women older than 70 are rarely treated for the disease, Kaplan noted.
In the United States, many women 75 and older simply don’t get mammograms, he said.
It’s a calculation that may have made sense when life spans were much shorter, Kaplan said. But now, at age 75, the average woman in the United States can be expected to live 13 years.
“It’s really pretty surprising if you’re healthy at 75 how much longer you’re expected to live. It’s very significant and very different than it was 20 years ago.”
Over the past 15 years, deaths from breast cancer have dropped by 30 percent, Kaplan noted. But it’s not clear whether the drop is a result of more widespread use of mammograms or better treatments.
As the population ages, the debate over mammograms becomes more critical, Kaplan said. “For all the debate about what’s appropriate for a 40-year-old, there is an analogous debate about what to do with a 70- or 80-year-old.”
Early diagnosis for invasive cancer is key, he said. “If they have advanced breast cancer, they do crappy, just like 24-year-olds. And if they have an extensive cancer, you can’t treat them, because they can’t tolerate the treatments as well.”
The American Cancer Society recommends that women continue mammography screening, the paper notes, as long as they have no serious chronic conditions or shortened life expectancy.
But at this point, there are no clear guidelines for mammography screening for women 75 and older, Kaplan said. “Even though our study is not a randomized trial, it’s indirect evidence that it’s probably a good thing to do.”
The research used Swedish’s breast-cancer patient registry, which has compiled records for more than 14,000 breast-cancer patients since 1990. More than 1,000 patients age 75 and older were identified and tracked for the study, which was funded by the Kaplan Cancer Research Fund, supported by patients and families.
Dr. Constance Lehman, director of imaging at Seattle Cancer Care Alliance, who was not involved in the research, said she was pleased with the paper’s conclusions and focus on older women.
“It’s an important study, a good study,” she said. “A lot of research groups say, ‘Who cares when they’re 75 and older?’ Well, we care! Many older women live incredibly active, vital lives.”
She sees many patients confused by the constant barrage of conflicting information about mammograms, she said. As a result, some just stop having them.
The disagreements among researchers are about which age to begin, the intervals for screening, and which age to stop, she said.
“But there is so much we all agree on,” she said, including that mammography offers a women the best chance for early detection. In older women, she said, the rate of false positives — which can lead to unnecessary diagnostic tests, including surgical biopsies — is very low.
But she noted that the study included women diagnosed with ductal carcinoma in situ (DCIS), a noninvasive breast cancer. Over time, while the incidence of more advanced Stage II and Stage III cancers detected by mammography dropped, the incidence of DCIS detected increased by 15 percent.
She’s worried about overtreatment in that group, she said, particularly in older women, where the cancer likely won’t progress significantly. Overtreatment is a serious concern, she said, because all treatments have risks, and particularly in older women, may affect quality of life.
“We’re treating women a lot the same,” when the women — and the cancers — are different, she said. “We think patients with DCIS are an ideal population in which to reduce overtreatment. I think there are very safe alternatives for low-intensity intervention.”
It’s difficult to quantify how many cancers could be safely ignored, Kaplan said. Computer simulations produce wildly varying estimates.
In the end, Kaplan said, he hopes the debates will lead to specific recommendations that take into account older women’s health and breast-cancer risk factors.