Annual mammograms really do save lives
A new study confirms what breast cancer researchers have been advocating for years: an annual mammogram has been shown to prevent 30% of breast cancer cases. The study of 130,000 women in two communities in Sweden is the longest-running study of its kind and shows that not only do regular mammograms prevent deaths from breast cancer, but also that the number of lives saved increases over time.
The study spanned almost thirty years, and researchers have found that the longer they looked, the more lives were saved. Radiologists have been quoting the study for years now in an effort to promote yearly screenings. However, the U.S. Preventive Services Task Force, an influential advisory group, recommended against yearly mammograms in 2009, creating a lot of confusion for patients and doctors alike.
The task force recommended scaling back the frequency of mammograms in women 40-49 because they sometimes produce “false positive” results – they come back with suspicious-looking lumps that turn out to be benign breast tissue. These then necessitate further screening and biopsies, resulting in a lot of stress, additional expense, and unnecessary pain. According to the panel, mammograms cut the risk of dying from breast cancer by about 15%, both for women in their 40s and 50s. But because younger women have such a low overall risk – the 10-year breast cancer risk for a 40-year-old is only 1.4% – their absolute reduction in death is very small.
Today’s announcement places the prevention rate at 30%. Robert Smith, director of cancer screening at the American Cancer Society and one of the study’s authors, says that false-positives are actually quite infrequent – less than 5%. Many groups, including the American Cancer Society, have stuck by their long-standing recommendations of a yearly breast exam for women starting at age 40, stressing that the breast X-rays have been proven to save lives by spotting tumors early, when they are most easily treated.
Professor Stephen Duffy of Queen Mary, University of London, the study’s chief researcher, said he thinks screening women 40 to 54 every 18 months and screening women 55 and older every two years would be a reasonable schedule. The new findings do not speak to the frequency of screening issue, but they do make clear that screening works.
"Everyone must make up their own mind, but certainly from combined results from all the screening trials, mammography in women aged 40-49 does reduce deaths from breast cancer," he said.
More than 193,000 American women will develop breast cancer this year, and 40,000 will die of it.
Breast cancer is the second-leading cause of cancer death among U.S. women, after lung cancer. It kills 500,000 people globally every year and is diagnosed in close to 1.3 million people around the world.
The study was published today in the journal Radiology.