LONDON (AP) - Amid an international debate over whether mammograms save lives, a major new study has reaffirmed that routine screening reduces breast cancer death rates by about 20 percent, experts say.

Many experts say the latest findings, published this week in The Lancet medical journal, should settle the issue.

Danish scientists have caused an uproar by analyzing 30 years worth of mammography studies and concluding they were so flawed that it's impossible to tell whether lives have been saved. The Danish researchers said the new report did not eliminate their doubts.

National breast cancer screening programs worldwide have been based on seven landmark studies done in the 1970s and '80s that concluded mammograms can cut deaths from breast cancer by 30 percent.

Debate became heated in October when Danish scientists reanalyzed those studies and concluded that five of them were so flawed that it is not possible to tell if routine mammograms save lives. An earlier version of their analysis, published two years ago, was widely dismissed.

Some of the most provocative of those original studies were done in Sweden, where researchers have come together to update their findings to provide results based on following the women for almost 16 years.

The group, led by Lenarth Nystrom, an epidemiologist at Umea University in Sweden, found that mammograms reduce the risk of dying from breast cancer by 21 percent in the long term.

The benefit was greatest for women in their 60s, who had a 33 percent less chance of dying from breast cancer if they were offered regular mammograms compared with women who were not.

Women aged 55 to 64 reduced their risk by 27 percent. Women older than 64 and those younger than 55 also benefited, but the results were not so clear for those groups.

Dr. Peter Greenwald, cancer prevention chief at the U.S. National Cancer Institute, said the NCI has independently reviewed all the evidence and reached similar conclusions.

"The original studies did have flaws, but the flaws are not big enough to refute the evidence that mammography saves lives," Greenwald said.

Other expert groups that recently have taken a fresh look at the decades-old studies have echoed that view.

Nystrom said the follow-up study was not done in response to the Danish concerns, but that extra information on the method was added to address some of the questions they raised.

Writing in a Lancet commentary on the work, experts from the British Columbia Cancer Agency in Vancouver, Canada said the study "reassures us that the Swedish data are believable and that they can be used to develop guidelines and assist individual women to make informed health care choices."

However, Dr. Peter Gotzsche, director of the Nordic Cochrane Center in Copenhagen, who conducted the review studies questioning the lifesaving benefits of mammograms, said the new research has not convinced him.

"Some of our very important concerns (about the methods) have still not been addressed," said Gotzsche.

"This is not an analysis of all the trials. One very good trial has been excluded and some trials we find problematic have been included," Gotzsche said. "It is more necessary than ever that the investigators give all their raw data to an international body that can analyze all the evidence together."

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 and how much to better treatment.

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

However, they are not perfect. They miss some cancer. They also too often flag benign lumps, causing unnecessary 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.

Experts say mammograms are not the only answer, but that the new research has reaffirmed their place.

Copyright 2002 The Associated Press. All rights reserved.