August 3, 2011 — Screening has been successful in reducing deaths from cervical cancer and colorectal cancer, but not breast cancer, according to the authors of a new European study published online July 28 in BMJ.
Reported by Fran Lowry Medscape News
Better treatment and improved healthcare-delivery systems are more likely to have led to reduced deaths from breast cancer than routine screening with mammography, lead author Philippe Autier, MD, from the International Prevention Research Institute, Lyon, France, told Medscape Medical News.
“Deaths from breast cancer are decreasing in North America, Australia, and most Nordic and western European countries, but it is difficult to tell whether this decrease is due to early detection from screening and early treatment, or whether it is due to better healthcare, he said. “We think it’s due to better care.”
However, his views are hotly contested by mammography experts in the United States.
Trends in Mortality
Dr. Autier and colleagues note that deaths from cervical cancer decreased substantially in Iceland and Finland after nationwide screening programs were initiated in the 1960s. However, in neighboring Norway, where screening programs were delayed, the reduction in mortality did not become apparent until many years later.
The team decided to see if something similar happened with breast cancer. Their hypothesis was that the reduction in mortality in countries that implemented mammography screening early would appear before the reduction in similar countries that started screening later.
To test this hypothesis, Dr. Autier and his team compared trends in breast cancer mortality in 3 pairs of neighboring European countries. In each pair, mammography had been introduced in one of the countries in or around 1990, but was not introduced in the other country until some years later. The pairs examined were Northern Ireland (United Kingdom) vs the Republic of Ireland, the Netherlands vs Belgium and Flanders, and Sweden vs Norway.
The researchers analyzed data from the World Health Organization (WHO) mortality database on cause of death from 1980 to 2006, as well as data sources on risk factors for breast cancer death, mammography screening, and cancer treatment.
The WHO data showed that breast cancer mortality decreased by 25% in the Netherlands, by 20% in Belgium, and by 25% in Flanders from 1980 to 2006. Breast cancer mortality decreased by 16% in Sweden and by 24% in Norway from 1980 to 2006.
Dr. Autier emphasized that “after 1989, the breast cancer mortality in these countries were comparable, despite a 10- to 15-year difference in the implementation of mammography screening.”
The downward trends in mortality started before or shortly after the implementation of mammography screening. The greatest reductions were in women 40 to 49 years of age, regardless of the availability of screening in this age group.
The fact that we don’t see any difference in mortality over time is a sure sign that mammography did not work very well,” Dr. Autier said. He added that these results were unexpected.
Mammography may do more harm than good
“We were surprised. We thought there might not be that strong an effect of mammography, but that we would see something. But we barely saw anything,” he said. “The main message is that we really have to work out what is going on with mammography screening in our population. We have plenty of data that screening for colorectal cancer and cervical cancer is worthwhile, but for breast cancer, it looks like mammography really doesn’t do the job.”
Mammography supporters ignoring the science
These views are hotly contested by the American College of Radiology (ACR), which immediately issued a statement declaring that “the conclusions of the BMJ study authors have little bearing on, or resemblance to, screening in the United States. Improvements in therapy have, likely, played a role in the decrease in breast cancer deaths, but therapy cannot cure advanced cancers. Early detection via mammography is clearly the major reason for the decrease in deaths in the United States.”
Carol Lee, MD, a spokesperson for the Breast Commission of the ACR and a radiologist in private practiced in New York City, told Medscape Medical News that she is “frustrated and bemused by continuing attempts to disprove what we’ve proved over and over again.”
Dr. Lee said: “We have a number of randomized controlled trials involving a half a million women over the course of many years that showed that screening with mammography results in decreased mortality from breast cancer. We’ve observed this in this country.”
Dr. Autier countered that the randomized trials that have found a benefit for mammography have been criticized for years because they are flawed.
Risk vs Benefit questioned
Weighing in with his opinion, John Keen, MD, attending radiologist at Cook County John H. Stroger Hospital in Chicago, Illinois, supported Dr. Autier’s assertion that the benefit of mammography is controversial.
“As usual, Dr. Lee won’t accept the evidence and remains the key mammography marketer for the ACR,” he told Medscape Medical News. “I noticed her new line of reasoning — that ‘therapy cannot cure advanced cancers.’ The problem here is that screening has not decreased the incidence of advanced cancer. Screening inherently misses the fast growing and catches the slow growing; hence, screening causes overdiagnosis with little mortality benefit,” he explained.
“Overdiagnosis of small screen-detected tumors that would never become clinically evident results in overtreatment with drugs and needless radiation, which can cause heart disease and increase future deaths,” Dr. Keen added.
“The trials have not shown any overall mortality benefit, nor is there any trial evidence to justify aggressive annual screening. Screening also increases overall mastectomies and lumpectomies because of overdiagnosis. The greatest benefit-to-harm ratio occurs for women in their 60s, which is what radiologists should be telling women.”
Dr. Autier, Dr. Destounis, and Dr. Keen have disclosed no relevant financial relationships. Dr. Lee is a spokesperson for the American College of Radiology. BMJ. Published online July 28, 2011. Abstract