Methods Used To Screen Breast Cancer May Be Doing More Harm Than Good

MAMMOGRAPHY'S $4-BILLION PROBLEM

Millions of women receive false-positive results annually, and 20,000 are over treated.

by Shannon Firth 
Contributing Writer

WASHINGTON -- For too many women, breast cancer screening does more harm than good, a researcher said here.

Kenneth Mandl, PhD, a professor at Harvard Medical School and director of the Boston Children's Hospital Informatics Program, and Mei-Sing Long, PhD, a research fellow at the hospital, examined the costs of false-positive mammograms and breast cancer overdiagnoses in the U.S. Mandl spoke at a Health Affairs panel about the cost and quality of cancer care Tuesday.

"There's a $4-billion problem, and it's $4 billion dollars being spent on two undesirable outcomes," he said, referring to false-positive results and overtreatment of breast cancer.

The magnitude of the financial problem will likely grab policymakers' attention first, but what's important is the human cost, he said.

"There are many women who are brave enough to face a false-positive thinking they that they are ultimately protecting themselves from cancer, and it's a small price to pay. The calculus changes if the protection from cancer is very small," Mandl told MedPage Today.

Providers, patients, and their families need to have a clear understanding of the facts around mammography screening, including "the magnitude of the benefit and the likelihood of the harm," he said.

Mandl and Ong obtained cost data from a major healthcare insurance carrier covering some 700,000 women 40 to 59 years old, who had undergone routine mammograms from 2011 to 2013. The data included demographic characteristics as well as all their medical claims.

The researchers excluded women receiving mammography for diagnostic reasons, those who had been screened within 9 months prior to the index screen, and women with a high risk of breast cancer, "since they may have been undergoing surveillance mammography instead of routine screening," the report noted.

Mandl and Ong defined a false-positive mammogram as a screening test that is later revealed not to be cancer, yet "exposes patients to additional diagnostic workup and psychological distress."

They define overdiagnosis as identifying lesions that are "unlikely to become clinically evident during the lifetime of a patient [that ] exposes patients to the harm of overtreatment." Amounts the insurance company paid to healthcare providers for patients' services, excluding copayments, coinsurance, and deductibles, were totaled to reflect costs of diagnosis and treatment.

False-positive findings were returned in 11% of the routine screening mammograms included in the analysis.

In the U.S., with 21.2 million women ages 40 to 49 and another 22.4 million 50 to 59, and with screening rates of about 62% and 73%, respectively, the researchers estimated that about 29.5 million women in these age groups received mammograms in a year. Using the false-positive rate of 11%, they calculated that nearly 3.2 million women would receive false positive mammograms each year, at a cost of $2.8 billion annually.

The researchers also calculated that in the 40-to-59 age group there would be 114,298 screen-detected cancers, of which about one-fifth would be ductal carcinoma in situ (DCIS) and the rest invasive tumors. Citing an overdiagnosis rate of 22%, based on recent studies, the researchers calculated that 20,116 women would be overdiagnosed with invasive breast cancer, at a cost of $1 billion each year. (Mandl and Ong were unable to determine which breast cancers were overdiagnosed using the claims data. "Thus we applied published overdiagnosis rates to determine the number of women who were likely to have been overdiagnosed," they noted in their report.)

"Here, we're talking about someone who's asymptomatic, not concerned about why they're sick, and not looking for a diagnosis," said Mandl.

The rate of overdiagnosis for ductal carcinoma in situ (DCIS) is a shocking 86%, according to the largest most recent study. For years, a DCIS finding automatically led to bilateral mastectomy, Mandl said. However, providers now realize that it often does not progress and sometimes is actually not even cancerous.

Mandl and Ong estimated the cost of DCIS overdiagnosis nationwide to be $243 million.

In total, they estimated costs of $1.2 billion in overdiagnoses for both invasive breast cancer and DCIS and another $2.8 billion for the workup and treatment costs associated with false positives.

Since 2009, the U.S. Preventive Services Task Force has recommended breast cancer screening every other year, for women ages 50 to 74. For women under 50 years old, the Task Force notes, "The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient's values regarding specific benefits and harms."

Ong and Mandl in their report's conclusion suggested that selective screening could benefit more patients than routine screening by age alone.

In selective screening, factors such as age, family history, genetic predisposition, breast density changes, and characteristics of mammography should help decide which women should receive screening, Mandl explained.

The idea is to limit screening to women for whom it clearly has a positive benefit-harm balance, although no specific algorithm for selective screening has been widely accepted.

In their Health Affairs paper, the researchers also noted that more research is needed "to develop risk-based stratification models" to prevent overtreatment of correctly diagnosed cancers and DCIS.

As for the impact of their report, Mandl said he hopes it will contribute to an understanding of the economics and explain why the "status quo" of current practices is so firmly entrenched.

"Any change in recommendation will shift the revenue one way or another and that has to be an explicit part of the conversation," Mandl said.via

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