In the latest study to question the benefits of mammographic screening for breast cancer, the authors of a study published online in the Annals of Oncology concluded that trends in advanced breast cancer incidence do not bear out that regular mammographic screening in parts of the world where it is available lead to a decline in mortality.
Lead author Philippe Autier, MD, of the International Prevention Research Institute (iPRI) in Lyon, France, and colleagues assessed incidence trends of advanced breast cancer in areas where mammography screening had been practiced for at least seven years with a minimum participation of 60%, and where there existed a population-based registration of advanced breast cancer.
Their work revealed differences between the results of randomized trials and screening mammography programs as applied in general populations, leading them to assert that the rate of advanced cancers can determine the impact of screening mammography. “Mammographic screening aims to detect cancer at an earlier stage that would be less life threatening and easier to cure than if detected clinically,” they write. Consequently, “a reduction of advanced cancer incidence should reflect the impact of screening activities alone, thus providing an estimate of the contribution of screening to the observed mortality decrease."
Aiming to look more deeply into studies stipulating that breast screening may increase the burden of low-risk cancers without reducing the incidence of more aggressive tumors, Autier's team executed a Medline search for data, published between January 1990 and June 2009, on incidence trends of advanced breast cancer in geographical areas with well-established mammography screening programs. Eight studies, published in peer-reviewed journals relating to mammography screening programs in Australia, Italy, the Netherlands, Norway, Switzerland, the U.K., and the U.S., were assessed. The percentage of all eligible women participating in mammography screening in these countries was founded to be fairly high, ranging from 60% in Italy to 88% in the U.S.
The study found age-adjusted annual percent changes to be stable or increasing in 10 geographical areas. Four areas exhibited transient downward trends, followed by increases back to prescreening rates. Breast cancer mortality fell after 1990 in all the geographical areas researched, with annual percentage changes ranging from –1.7% to –2.5%. However, such decreases in mortality frequently started before the screening program began, or before it was offered to a majority of women, the researchers wrote.
Additionally, the team conducting the research anticipated declines in the incidence rate of advanced breast cancer correlating with the implementation of screening programs. However, they instead noted little change in advanced breast cancer incidence rates, despite seven to 15 years of fairly high-level patient participation in mammography screening.