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General interest items edited by Janice Flahiff

[Reblog] Could finding more cancer lead us to understand risk factors less?

From an article at the blog, by Michael Joyce

An opinion piece in last week’s Annals of Internal Medicine argues that just how aggressively we screen for some cancers can actually distort our understanding of the risk factors for a particular cancer, as well as how common we perceive it to be.

The authors describe ‘scrutiny-dependent’ cancers  — those subtypes of cancers often picked up with screening that are commonly referred to as slow-growing, indolent, subclinical, or even as pre-cancerous — and that often don’t progress to cause health problems or shorten lives. Prostate cancer and thyroid cancer are two such examples.

They propose two common ways in which aggressive screening can distort our understanding of these cancers:

  • The push for ‘early detection’ leads to more scrutiny-dependent cancers being found which, in turn, gives the false impression of an increased incidence of some cancers.
  • Aggressive screening of the family members of someone with cancer means more cancer will be found. This could give the impression of family history being more of a risk factor than it may actually be.
  • Breast cancer found by mammography, ultrasound, or MRI is more likely to be indolent than that found by self-examination. As we screen with more advanced technologies capable of finding smaller and smaller tumors, we will find more cases of cancer but also more cases that don’t develop into cancer. This not only represents overdiagnosis, but can also give the false impression of breast cancer being more common than it really is

“In the 80’s and 90’s the prevailing message from the media was screen, screen, screen,” said Brawley. “Only in the past 10-15 years have some reporters begun to question this. And this goes for advocacy groups too, who have an understandable emotional conflict of interest because they care about a particular disease. I know, I work for one. But, both reporters and advocates need to be truthful and accurate about screening. Because people can get hurt.

In short, Welch and Brawley firmly believe that screening should be based on rigorously tested evidence. In some cancers that evidence is clear, while for other cancers (‘scrutiny-dependent’ ones) the evidence is lacking. Media messages about cancer screening need to do a better job communicating that uncertainty. 

January 9, 2018 - Posted by | health care | , , , ,

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