THURSDAY, Dec. 8, 2011 (HealthDay News) -- Women aged 40 and older who follow recommendations to have annual mammograms may do themselves more harm than good, British researchers report.
Study author James Raftery, a professor of health technology assessment at the Wessex Institute at the University of Southampton, said that "this is due to reduced quality of life of those who receive diagnoses that turn out to be false and to those who are treated unnecessarily."
Women who plan to have a mammogram should be aware of the balance of harms and benefits and take these into account in deciding whether to get one or not, he said.
"Be aware of the harms as well as the benefits of breast cancer screening," Raftery said.
When and how often mammography screening makes medical sense is currently being debated in the United States and elsewhere. Some experts think women should start getting them at age 40, while others believe routine screens should not begin until a woman is 50.
The British report was published in the Dec. 8 online edition of the BMJ.
Raftery and his colleague, research fellow Maria Chorozoglou, reviewed a 1986 report titled the Forrest Report. That report led to the introduction of breast cancer screening in the United Kingdom, they noted.
That report tried to estimate the number of screened and unscreened women surviving each year over 15 years. The costs and benefits of screening were measured in quality adjusted life years, which combines measures of length and quality of life, but the report omitted any harms from screening, the researchers noted.
The report suggested screening would reduce the deaths from breast cancer nearly one third with few harms and at low cost.
To see if these predictions panned out, Raftery and Chorozoglou tried to update the survival estimates of the report, but this time taking into account both benefits and harms.
Their results are based on 100,000 women aged 50 and older surviving up to 20 years after they started screening.
When the researchers included data on false positive tests and unnecessary surgery, the benefits of screening were cut in half.
Their best estimates found a negative quality of life measurement for up to eight years after screening, and only modest gains after 10 years.
After 20 years, the quality of life benefits improved, but much less than the Forrest Report had predicted, they found.
"From a public perspective, the meaning and implications of overdiagnosis and overtreatment need to be much better explained and communicated to any woman considering screening," the researchers concluded.
Dr. Julie Gralow, director of breast medical oncology at the University of Washington in Seattle, disagreed strongly with the new study findings.
"The cumulative evidence from randomized clinical trials shows the screening mammograms reduce deaths due to breast cancer," she said. "This is objective fact."
The effects of the harms of a false positive mammogram are very subjective, Gralow added. "A call-back for additional views is expected in a certain percentage of women; many times the extra images are enough to resolve the problem without a biopsy," she said.
"If you want to catch as many cancers at an early stage as possible, you have to follow up on anything of moderate suspicion. Many women understand this and accept it," Gralow said.
A biopsy, which is rarely done surgically any more, that shows benign disease has the potential for some psychological harm, Gralow acknowledged. "But it can't possibly be weighed equally or even close to equally against saving a life," she said.
"For many women surgery for a low-risk breast cancer is just not a big deal," she added. "I'd equate surgery for low-risk breast cancer with removing a colon polyp. It may or may not cause trouble if not removed, but it usually means you have a higher risk of development of a cancer in another location."
The benefits beyond lives saved are missing from many of the recent analyses of screening mammograms, Gralow said.
"Finding a cancer at an earlier stage, when it is smaller, and before it travels to the lymph nodes or beyond, means less chance of mastectomy and more chance of lumpectomy, less need for chemo or other drugs, less need for radiation, etcetera. Needing less aggressive therapy is a big bonus, and that's hard to calculate into the equation," she said.
Another expert, Dr. Kristin Byrne, chief of breast imaging at Lenox Hill Hospital in New York City, added that the new British "study is absolutely wrong."
Women should have a yearly mammogram, Byrne said. "It's studies like this that confuse us. It confuses physicians, it confuses patients," she said. "We know that mammograms reduce mortality by 30 percent."
For more on breast cancer, visit the American Cancer Society.