Women who participated in at least three screening mammograms had a 49 percent lower risk for breast cancer mortality, a new case-control study published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, showed.
"Our study adds further evidence that mammography screening unambiguously reduces breast cancer mortality," said Suzie Otto, Ph.D., a senior researcher in the department of public health at the Erasmus MC at Rotterdam in the Netherlands.
Otto and colleagues observed 755 patients who died from breast cancer during 1995 to 2003 and matched them with 3,739 controls. Among the breast cancer cases, 29.8 percent were detected at screening, 34.3 percent were detected between screenings and 35.9 percent had never been screened.
Stage IV tumors were present in 29.5 percent of the never-screened cases but only 5.3 percent of the screen-detected cases.
If women attended at least three screenings prior to diagnosis, their risk for mortality from breast cancer reduced by 49 percent. The greatest reduction was seen in women aged between 70 and 75 years old, where the reduction in mortality was 84 percent. Among younger women (aged 50 to 69 years old), the reduction was smaller, at 39 percent, but still statistically significant.
Otto said the findings could be applicable in the United States in principle, but the United States lacks a a centrally organized government-funded program similar to what is found in the Netherlands.
"The Dutch government considers it imperative that everyone eligible for a screening program is given the opportunity to participate," said Otto. "For that reason, all women in the targeted age group are invited and given the opportunity to decide independently to participate or not in screening programs that are entirely free of charge."
Otto and colleague's study was funded by the Dutch Health Care Insurance Council and the National Institute for Public Health and the Environment.