Concerns raised about the benefits of cancer screening ... again.
We've had this conversation a lot here at Picture of Health when it comes to breast and prostate cancer: to screen or not to screen?
We've explored studies that expressed some doubts about the benefits of mammography, that some women overestimate the mortality reduction of breast cancer screening and that studies have shown that approximately 1 life is saved for every 1,000 mammograms given.
And we've discussed the debate over prostate cancer screening and whether the disease is being overdiagnosed, exposing men to potentially harmful treatment for cancers that may pose no harm to them in the long run. Another recent study showed that some men may not be getting the counseling from their doctors that they need to understand the risks.
So it didn't surprise us when an NYT story reported yesterday that the American Cancer Society is reconsidering its screening guidelines for breast and prostate cancer. And a new editorial in the Journal of the American Medical Association raises similar doubts, finding that such screenings are turning up more cancers that may never hurt people.
We wondered, though, is this really a shift in philosophy?
The idea that screening saves lives is not as simple as it sounds, and the advantages of screening have been "exaggerated," Dr. Otis Brawley, chief medical officer at the American Cancer Society told the Times.
The NYT story created quite the buzz yesterday, so much so that the cancer society clarified its stance on breast and prostate cancer screening, saying that while the benefits of some screening have been overstated, mammograms for women 40 and over are still encouraged.
I've talked to Brawley about this concept before -- that people can have cancers that may never kill them and never pose them harm. And sometimes, treating those cancers exposes the patient to harmful and unnecessary treatment. His major point, I believe, was that clinicians should exercise caution and that patients should be aware of the benefits AND the potential risks.
Brawley underscored those points on NPR this morning, specifically regarding prostate cancer screening: "I and the American Cancer Society are not against screening, but we're for men knowing that there are some questions here as to whether screening is effective and then making a decision that they are comfortable with."
Associated Press photo
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Breast screening: the facts—or maybe not ...
From the British Medical Journal:
http://www.bmj.com/cgi/content/full/338/jan27_2/b86
Consequences of imbalance
The one sided propaganda about breast screening is a global phenomenon that has resulted in misconceptions about its effects. A survey of American and European women found that 68% believed screening reduced their risk of contracting breast cancer, 62% that screening at least halved mortality, and 75% that 10 years of screening saved 10 of 1000 participants (an overestimate of 20 times). Another study showed that only 8% were aware that participation can harm healthy women18 and that 15% believed their lifetime risk of contracting the disease was more than 50% (an overestimate of five times).
A recommended informational leaflet for women:
# It may be reasonable to attend for breast cancer screening with mammography, but it may also be reasonable not to attend because screening has both benefits and harms
# If 2000 women are screened regularly for 10 years, one will benefit from the screening, as she will avoid dying from breast cancer
# At the same time, 10 healthy women will, as a consequence, become cancer patients and will be treated unnecessarily. These women will have either a part of their breast or the whole breast removed, and they will often receive radiotherapy and sometimes chemotherapy
# Furthermore, about 200 healthy women will experience a false alarm. The psychological strain until one knows whether it was cancer, and even afterwards, can be severe
Posted by: Ed Dwulet | October 23, 2009 12:15 AM
Hi! I also heard about the screening may cause a real risk of overtreating small cancers while missing the cancer deadly.
But, i still don't really understand about this. Can you please explain to me how the screening process will harm us? Is it the chemical drug we use? Thanks for information.
Regards,
Kok Siong
Cytogenetics and Cancer
Posted by: Kok Siong Chen | October 23, 2009 1:02 AM