A new study has found annual mammography screening of women in their 40s reduces the breast cancer death rate in these women by almost a third.
The landmark breast cancer screening study of women aged 40 to 49 has been published online in the journal Cancer.
Around the world, most women begin mammogram screening at the age of 50. In Australia, women are offered free mammograms from 50 to 69 years.
But the authors of this new study say the use of the age of 50 as a threshold for breast cancer screening is scientifically unfounded. "Women should begin getting annual mammograms at age 40," the authors say.
The trial followed more than 600,000 Swedish women from 1986 until 2005.
The number of breast cancer deaths among the women in the study who did not receive mammograms was 50% higher than those who underwent screening. This translated into an increased relative risk of 26% to 29% for woman who were not screened.
"This study, which looked at the performance of screening mammography as it is actually used, rather than relying on mathematical modelling, shows without a doubt that mammography decreases deaths from breast cancer in women aged 40 to 49 by nearly one third," says Dr Carol H Lee, Chair of the American College of Radiology Breast Imaging Commission.
"There is no excuse not to recommend that average risk women begin annual screening mammography at age 40."
Younger women are not routinely offered mammograms because their breast tissue is dense and lumps are harder to detect. Younger women are more likely to be offered breast ultra-sounds.
"This study shows that annual mammograms for women 40 and over result in a tremendously significant reduction in the breast cancer death rate for women 40 to 49," says Dr Phil Evans, President of the Society of Breast Imaging (SBI).
"The age of 50 is an artificial threshold that has no basis in scientific fact. The debate is now over. Women should no longer be confused about the importance of annual breast cancer screening. Mammography saves lives."
In Australia, women aged over 50 are offered mammograms every two years.
Breast cancer is the second most common cause of cancer-related death in Australian women, with 2618 women dying in 2006. The lifetime risk of women developing breast cancer before the age of 75 is one in 11.
Experts say well organised mammographic screening can substantially reduce the number of deaths from breast cancer.
"What providers need to do now is uniformly confirm for women that they need to start getting annual mammograms beginning at age 40 and work to build on the ability of mammography to detect cancer early, when it is most treatable," says Dr Gail Lebovic, breast surgeon and President of the American Society of Breast Disease (ASBD).
"Mammography saves a significant number of lives in all women 40 and over. Let's all move forward from there."