The benefits of breast cancer screening are vastly overestimated as the figures do not back them up in practice, scientists who conducted an in-depth review of principal trials have said.
The team looked at studies on screening for breast, colorectal, cervical, prostate and lung cancers that were started in Sweden in the 1960s and 70s.
They suggested that mammography could reduce deaths by 20 to 25%, the results of which made breast cancer screening more widespread.
But the new research found that rates have not actually decreased as much as expected.
Lead author, Professor Philippe Autier, of the University of Strathclyde’s Institute of Global Public Health, said: “Contrary to expectations, numerous studies in North America, Europe and Australia have shown that the rates of advanced breast cancer have not declined in countries where most women regularly attend mammography screening.
“Other studies have shown that declines in breast cancer mortality were the same in countries that implemented mammography screening end of the 1980s as those that did so 10 to 20 years later. The absence of differences in mortality reductions could not be explained by differences in access to modern therapies.”
Scientists said if these trials had used similar statistical analyses to other cancer screening trials, reductions in the risk of breast cancer death associated with mammography screening would have been much smaller, and probably less than 10%.
Professor Richard Sullivan, from the Institute of Cancer Policy at King’s College London, said: “These findings were in sharp contrast with screening for cervical and colorectal cancers, two cancers for which studies have clearly shown the capacity of screening to reduce the numbers of advanced cancers in populations.
“This has major implications for policy-makers in middle income countries who are now making decisions about where to prioritise cancer screening efforts”.
The research is published in the Journal of the Royal Society of Medicine.
Breast cancer screening in women between the ages of 50 and 69 led to a 40% reduction in deaths from the disease, a major review co-ordinated by the International Agency for Research in Cancer (IARC) found last month.