Women Confused by Conflicting Mammogram Data

If you’ve ever wondered whether to take medical advice from the federal government, the renewed controversy over mammograms might help resolve that dilemma.

A panel of the National Cancer Institute quietly concluded in mid-January it isn’t sure routine mammograms for 40-something women reduce the risk of dying from breast cancer.

The NCI’s "PDQ" panel now says, "Studies have found that screening mammography is beneficial in women aged 50 to 69. Screening in women younger than 50 years or older than 69 years may or may not be helpful."

This contrasts dramatically with official NCI policy, reiterated after the panel’s decision. "NCI believes early detection is one of the most important approaches to cancer control. NCI recommends mammography for women starting in their 40s," said the NCI’s director of cancer prevention.

What’s a woman – even her physician - to make of this? Is this the National Cancer Institute or the National Confusion Institute?

There’s no doubt mammography saves lives. This fact, however, does not answer the question of whether 40-something women should have mammograms every 1 or 2 years. Routine mammography entails costs and risks to be weighed with the possibility of benefit.

Breast cancer risk is relatively low among 40-something women; but it increases with age. At 40, breast cancer risk is estimated at 1 in 235; at 50, the risk increases to 1 in 54, according to the NCI.

At costs ranging from $100 to $150, mammograms find tumors that cannot be felt. But this may not save a life if the tumor is aggressive and has already spread to other parts of the body.

Mammograms miss about 20 percent of cancers present at the time of screening.

About 5 to 10 percent of the 30 million annual mammograms are read as abnormal, even though no cancer is present. These "false positives" cause additional testing, including fine needle aspiration, ultrasound and biopsy. About 800,000 biopsies are taken every year.

You might think that after hundreds of millions of mammograms, there would be little uncertainty about the costs and benefits of routine mammography.

Unfortunately, though, the NCI has been asleep at the switch when it comes to collecting good data on mammography, leaving women at the mercy of the $3 billion mammography industry.

Mammogram-mania began in 1985 when Swedish radiologist Dr. Laszlo Tabar claimed breast cancer deaths could be cut by almost 40 percent with routine mammograms.

In 1989, the mammography industry lobbied the American Cancer Society, the American Medical Association and the NCI to recommend routine mammography for 40-something women - even though the cost-benefit data were unclear and a 1987 AMA panel refused to recommend routine mammograms for younger women.

The effort paid off. The number of annual mammograms increased from 10 million to about 30 million during the 1990s.

All went well for the mammography industry until a National Institutes of Health panel concluded in February 1997 that the costs of routine mammography for 40-something women outweighed the benefits. This conclusion sent the industry into orbit. It lobbied Congress for an inquisition of the NIH.

The Senate demanded the NIH chairman defend the panel’s conclusion and then voted 98-0 to support mammograms for 40-something women.

The Senate intimidated the NCI into assembling a panel that soon concluded the benefits of mammography outweighed the costs for 40-something women. The NCI panel offered no new data to account for the different conclusion.

The controversy was stifled until last year when two Danish researchers reported in the medical journal The Lancet that existing studies on mammography were poorly designed and did not show that routine mammography reduced women’s death rates. This research helped spur the PDQ panel to revise its recommendation.

Now in response to the PDQ panel’s recent revision, the mammography industry is back in damage control mode. An analysis rushed to publication by cancer screening advocates in this week’s The Lancet challenges the conclusion of the Danish researchers.

The new analysis claims that the Danish researchers misread their data and that the benefits of routine mammography don’t show up until seven years after it begins.

But the numbers of deaths comprising the new analysis are so small (single digits in almost all years) that the comparisons are statistically and scientifically meaningless.

Where does all this leave 40-something women? The answer is not very comforting.

Routine mammography may save a woman’s life. It may not. There is no clear answer right now.

Women – in consultation with their physicians - need to weigh for themselves the benefits of screening with its risks and costs. The confused NCI bureaucracy and mammography industry should be omitted from this decision-making process.

Instead of making contradictory recommendations based on poor quality data, perhaps the NCI could spend some of the taxpayers’ $766 million allocated for breast cancer research on collecting mammography data that means something.

Steven Milloy is the publisher of JunkScience.com, an adjunct scholar at the Cato Institute and the author of Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).