This story includes strong comments from independent experts that can help readers get a broader understanding of the results of a study that compared breast cancer death rates among women in their 40s who lived in areas of Sweden that did or did not offer routine mammography. However, because the story reports only the percentage difference in death rates, without including absolute numbers or the number of women who need to be screened to prevent one death, readers may get the impression that the effect of mammography was larger than what the researchers actually reported.
People commonly overestimate the risk of breast cancer death among women in their 40s. By not including any information about the absolute numbers of deaths among women in this study or in the population at large, the story misses an opportunity to correct common misconceptions.
The story does not discuss the costs of annual mammography screening, or even provide a range of costs. The story does not discuss any health care policy cost repercussions of breast cancer screening recommendations. The story does not discuss the cost of unnecessary biopsies or other treatments for women who have a false positive diagnosis via mammography (greater in women 40-49).
The story highlights the 26 percent difference in breast cancer death rates, but fails to include any information about the overall risk. The researchers reported that based on their results you would have to screen 1252 women for a decade in order to prevent one breast cancer death. In other words, for the remaining 1251 women, a decade of mammograms did not alter their breast cancer mortality.
Although this story does not go into detail about the potential harms of screening mammography, it does include comments from independent experts who point out that the scans do lead to the diagnosis and treatment of women whose tumors would never have become life-threatening.
This story briefly explains key features of this study. It also includes critiques from independent experts who note limitations of the study design and analysis – although the statement that the researchers "did not compare the broader breast cancer death rates" in the counties" is unclear. Overall, there is much more the Times could have done to analyze methodological questions surrounding the Swedish study. (For example, read our blog on this matter.) Interviews with Peter Gotzsche and with Donald Berry saved the story. But so much more could have been done – another reason why more than 471 words should have been devoted to the reporting.
The story does not discuss the prevalence of breast cancer among women in their 40s. That omission would not usually be considered disease mongering, but since surveys indicate most people overestimate the risk of breast cancer among women in their 40s, failing to mention the actual rates leaves those misconceptions intact.
The story does include comments from experts who raise concerns about overdiagnosis; that is, the number of breast tumors discovered that are not actually life-threatening.
A strong point of this story is the inclusion of comments from several independent experts with a variety of perspectives on the meaning of the latest study results. The story does not mention any potential conflicts of interest, but the researchers did not list any in their journal article.
Although not discussed in detail, the story does mention that the United States Preventive Services Task Force has questioned the value of screening mammograms for women younger than 50, thus implying that not being screened is an option to consider.
The availability of mammography was not explicitly addressed, but we can’t criticize the story for that. Instead, we give a Not Applicable score for this criterion.
This story could have done a better job explaining how this study – and its methods – are different from earlier research on the topic.
But two things lead us to give it a barely satisfactory score. First, there was a brief attempt to mention the unique "circumstances" of the Swedish study. Second, the story also pointed out that there’s a historical ideological pattern in the study authors’ work – noting that they "have long been advocates of mammography screening."
It’s clear that the story was not based on a news release.