The decline in breast cancer mortality in Sweden is not associated with the country’s nationwide breast cancer screening program, researchers say.
The decline in breast cancer mortality in Sweden is not associated with the country’s nationwide breast cancer screening program, according to an article published today in the Journal of The National Cancer Institute.
Sweden initiated a screening program, beginning in 1974 and peaking in 1997, to provide nationwide coverage for mammography for women aged 40 to 69 years old. It was hypothesized that this coverage would result in a drop in breast cancer mortality. To determine if this was true, researchers analyzed the trends in breast cancer mortality in 1995 and 1996 in more than one million women this age group, dividing them by the counties in which they lived.
Interestingly, the researchers found that the mortality rate began to decrease in 1972, before the 1974 onset of the nationwide screening programs. The rate continued to decrease at a similar rate after the screening program was initiated.
“It seems paradoxical that the downward trends in breast cancer mortality in Sweden have evolved practically as if screening never existed,” wrote the authors.
The researchers reported that from 1972 to 2009, breast cancer mortality in the study group declined by 0.98 percent annually, from 68.4 percent to 42.8 percent per 100,000. The mortality rate continuously declined in 14 of the 21 Swedish counties.
In counties that initiated screening in 1974 to 1978, mortality trends over the next 18 years were no different from before the screening years. In counties where screening began in 1986 and 1987, mortality increased after screening began.
In counties that began screening in 1987 and 1988, mortality declined by approximately 5 percent, and in counties that began screening in 1989 and 1990, mortality declined by 8 percent.
“It is time to move beyond an apparently never-ending debate on at what extent screening for breast cancer in itself conducted in the seventies through the nineties of the last century has reduced mortality for breast cancer, as if it was isolated from the rest of health care,” wrote the authors. “The presence of an organized screening program may have promoted the provision of more effective care by monitoring the treatment quality of screen-detected cancers and by favoring the creation of multidisciplinary unites of breast cancer specialists.”