A new study published in the New England Journal of Medicine is questioning the effectiveness of mammograms. The study claims mammography screening for early signs of breast cancer does work and can save lives, but it may not be as effective as some believe.

The study followed more than 40,000 Norwegian women with breast cancer. Researchers state the numbers showed mammograms may not save lives as once predicted.

"They expected the mortality rate to be reduced by 30 per cent after 10 years. So after 10 years we wanted to see if that was the case. And finding 10 per cent reduction, instead of 30 per cent reduction was a surprise to us," said the study's co-author Dr. Mette Kalager of the Harvard School of Public Health.

The study showed if 2,5000 women got regular mammograms over a period of ten years, it would prevent one woman from dying of breast cancer. But that leaves thousands having what researchers call "necessary testing and anxiety."

"This study tells us that we are getting more and more evidence that the consequences of breast screening programs for women are not doing as much for women as they think they are," said Dr. Cornelia Baines with the University of Toronto's Department of Public Health Sciences.

Researchers also state that some women may be over-treated with surgery, radiation, and chemotherapy, when their breast tumours may have gone away on their own.

"There's no right answer It's something all women have to recognize.This is a close call and different women can make different decisions," said Dr. Gilbert Welch of Dartmouth Institute for Health Policy.

Here in Edmonton, Marilyn Polny gives mammograms to hundreds of women each year. And she strongly supports the technology.

"Instead of having a yearly mammogram post menopausal they're saying every two years, but I come every year," she said.

Polny fears studies such as this one may keep some women from getting a mammogram.

"We have to go with what the experts say but mammography is still the gold standard for diagnosis," she said.

Dr. Welch doesn't feel the current advice being given to women about mammograms will change overnight. He does state however, that the debate is long from over.

"Mammograms remain a critical tool for finding out if a breast lump is actually cancer. But its role to find small growths is increasingly coming under scientific scrutiny," he said.

With files from Dez Melenka and CTV.ca News Staff