LONDON (Reuters) – Nordic scientists said yesterday they had found no evidence that screening women for breast cancer has any effect on death rates, adding to an already fierce international debate about routine testing.

In a study published in the British Medical Journal, researchers from Denmark and Norway said reductions in breast cancer death rates in regions with screening were the same or actually smaller than in areas where no women were screened.

"Our results are similar to what has been observed in other countries with nationally organised programmes," said Karsten Jorgensen of the Nordic Cochrane Centre in Copenhagen, who led the research. "It is time to question whether screening has delivered the promised effect on breast cancer mortality."

A row blew up in the United States in last November after public health officials on the US Preventive Services Task Force questioned the value of screening mammograms for women under 40 and suggested raising the annual screening age to 50.

Cancer doctors and advocacy groups denounced the move, saying the changes would mean more women would die from breast cancer. Some lawmakers said they may be used to ration healthcare. Breast cancer is the most common cancer in women worldwide, accounting for around 16 percent of all female cancers. It kills around 519,000 people globally each year. Jorgensen said that although breast cancer screening programmes vary by country, Denmark was a good benchmark and his team's findings should inform the debate. In Denmark, women are screened every two years from age 50, while in the United States mammograms are now recommended every one to two years for women aged 50 plus, and in Britain the policy is for women over 50 to be screened about every three years.