April 25, 2003

LONDON (AP) -- Women who get regular mammograms could reduce their risk of dying from breast cancer by 28 percent, new research indicates.

The study is the largest and most rigorous yet to investigate the survival benefits of routine breast X-rays. Conducted by a team of scientists from Sweden, Britain, Taiwan and the United States, the research was based on 210,000 women aged 20 to 69 in Sweden.

Breast cancer deaths in the United States and Europe have fallen by nearly 30 percent since 1990. Experts are not sure how much of this is due to catching the disease early with mammograms.

"While mammography is largely accepted by the scientific and medical community as a benefit to women, there are still some who express doubts as to its value. This study goes a long way toward silencing the dissenting voices," said the study's leader, Stephen Duffy, professor of epidemiology at the Wolfson Institute of Preventive Medicine in London.

However, other experts said that the research, published this week in The Lancet medical journal, does not clarify whether the drop in deaths is due to early detection from the X-rays or simply advances in treatment.

"I just don't buy that the degree of benefit attributed to mammography is as high as they say," said Dr. Peter Greenwald, cancer prevention chief at the U.S. National Cancer Institute.

Still, Greenwald said the findings are worth taking into account.

"It's an important study. It's a large study, and it shows that in an entire population there's a drop in the death rate, which is very good," Greenwald said.

Recommendations that women have regular mammograms have been based on seven landmark experiments conducted in the 1970s and 1980s that concluded the X-rays can cut deaths from breast cancer significantly.

However, confidence in breast screening was shaken by Danish scientists in 2000 who reanalyzed the experiments and concluded five were so flawed it was impossible to tell if routine mammograms saved lives.

Several expert panels also concluded the studies were flawed, but not so dramatically that they dismissed their conclusions supporting mammograms. However, their opinions varied about the number of lives mammograms saved.

In the latest study, researchers compared deaths from breast cancer diagnosed in the 20 years before mammogram screening was introduced with those diagnosed in the 20 years afterward. The X-rays were introduced in 1977 and offered to all women over 40.

During that time, 8,551 women developed breast cancer and 2,143 of them died from the disease.

The study found that, among women who got regular mammograms, the risk of dying from breast cancer was reduced by 44 percent compared to the early 1970s, when mammograms were not routinely done.

However, women who refused mammograms still saw a 16 percent reduction in the chance of dying from disease. That means their improved survival chances must have been due to factors other than mammography, such as better drugs.

Donald Berry, chair of biostatistics at the M.D. Anderson Cancer Center in Houston, said he believes screening has a benefit but says improvements in drugs and treatment likely have had a bigger impact.

"The strides that have been made in breast cancer treatment are enormous. They dwarf those of practically every other cancer ... (and) could well account for the reductions in breast cancer mortality seen," Berry said.

Mammograms can detect small tumors up to two years earlier than breast exams, providing more options for treatment.

However, they miss some cancer. They also too often flag benign lumps, causing anxiety, additional testing and biopsies.

Over 10 years of screening, about 23 percent of women will have an abnormal mammogram result and about 80 percent of those will be false alarms.

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