Why Cancer Screening Can Cause Harm

[Christine]

Published August 21, 2007

Last year, a research study on lung cancer screening published in the New England Journal of Medicine made big news.

The authors claimed that doing CT (“cat”) scans to look for lung cancer in high-risk people (mostly smokers) resulted in a significant improvement in survival.

A study published a year later, by contrast, received hardly any publicity at all — maybe because it came to the opposite conclusion.

A team led by Dr. Peter B. Bach of Memorial Sloan-Kettering Cancer Center in New York published its own study in the Journal of the American Medical Association (March 7, 2007).

It was accompanied by an insightful editorial by Drs. William C. Black and John A. Baron of Dartmouth.

Dr. Bach’s team looked at 3,246 people who were either smokers or former smokers screened with annual CT scans and then followed up for approximately four years.

They used a mathematical model, shown to be highly reliable in other studies, that predicted the expected numbers of cases and outcomes from lung cancer in such a group.

The team discovered that the CT-scan screening picked up about three times as many cases of lung cancer as would have been expected without it.

That sounds like a huge success, right?

They also found that there was no improvement in the number of cases of cancer that were very advanced at the time of diagnosis; and there were no fewer deaths from lung cancer.

However, ten times as many people in the screened group ended up having major lung surgery compared with the expected rate.

So why did the New England Journal study show apparent improvement in survival, when the Bach study showed no real benefit from picking up more cases earlier?

Drs. Black and Baron went into great detail comparing the two studies and made a good case that the Bach study was simply much better done and therefore was more reliable.

Black and Baron admitted that the real answer is simply not in yet.

Neither of the two previous studies used the most reliable method — randomly assigning high-risk patients to screening or no screening, and then following them long-term.

Two such studies are now under way, so stay tuned.

Meanwhile, the take-home message is a sobering reminder that, sometimes, a fancy screening test can lead to a much higher chance of having yourself cut open in a rather painful way, with nothing to show for it afterwards in terms of improved length or quality of life.

Dr. Howard Brody, a family physician, is director of the Institute for Medical Humanities at UTMB.

[twodogs]

If I read the report right, Dr. Bach can kiss my bachside. After a year of unexplained pain, cough, allergic reactions and malady after malady an ER doctor finally wouldn't let me go home until he did the Spiral CT.

Bingo. SCLC with SVCS.

When I asked why nobody else caught it earlier he simply stated that insurance wouldn't pay for the CT as a regular procedure. They'd pay for misdiagnosed neurological surgery or spinal surgery along with MRI's, etc. etc., though.

JMO

John

[recce101]

"twodogs" If I read the report right, Dr. Bach can kiss my bachside.

That was a nice POW. But watch out, 'cause if you get me started you're gonna have some tough competition for first in line!

Aloha from Ned

[ernrol]

You may find that the people that consented to the CT scans were people those themselves thought they were more likely to have cancer. So the CT group was heavily loaded with high risk people. This would account for a higher ratio of cancer from the Ct group.

Stay positive,

Ernie