Among older women, getting a mammogram every two years was as beneficial as getting a mammogram annually, and led to significantly fewer false positive results, according to a study.
“Screening every other year, as opposed to every year, does not increase the probability of late-stage breast cancer in older women,” Dejana Braithwaite, PhD, the studys lead author and an assistant professor of epidemiology and biostatistics at the University of California, San Francisco, said in a news release. “Moreover, the presence of other illnesses such as diabetes or heart disease made no difference in the ratio of benefit to harm.”
The national study of more than 140,000 women ages 66 to 89 is scheduled for publication in the Journal of the National Cancer Institute.
From 1999 to 2006, researchers collected data on 2,993 older women with breast cancer and 137,949 women without breast cancer, making the study “the largest available screening mammography data set in the United States,” Braithwaite said.
The researchers found no difference in rates of late-stage breast cancer between women screened annually and women screened biennially.
However, they found that 48% of women ages 66 to 74 who were screened every year had false positive results, while 29% of women in the same age range who were screened every two years had false positives.
Women in that age group “who choose to undergo screening mammography should be screened every year two years,” said Karla Kerikowske, MD, the studys senior author and a professor of medicine at UCSF.
“They get no added benefit from annual screening, and face almost twice the false positives and biopsy recommendations, which may cause anxiety and inconvenience,” added Kerlikowske, also a physician at the UCSF-affiliated San Francisco VA Medical Center.
Taken together, “these results point to a need to consider life expectancy and co-existing illnesses in informing future recommendations about cancer screening in the elderly,” Braithwaite said.
The study abstract is available at http://jnci.oxfordjournals.org/content/early/2013/02/01/jnci.djs645.abstract.