August 9, 2005

THEY MAY BE SMALLER FOR A REASON:

Smaller tumors linked to breast-cancer survival (Marilynn Marchione, 8/09/05,
ASSOCIATED PRESS)

The odds of surviving breast cancer have improved in recent years, not only because treatments are so much better, but also because the average tumor is smaller, a major new study shows.

Examining 25 years of cancer records nationwide, researchers concluded that smaller tumor size accounted for 61 percent of the improvement in survival when cancer had not spread beyond the breast, and 28 percent when it had spread just a little.

For women 65 and older with early-stage tumors, the most common scenario, the shift in size accounted for virtually all of the improvement in survival.

"We don't in any way want to diminish the benefits we've seen from advances in treatment, because they've been enormous," said lead researcher Elena Elkin. "But not all of the improvement in survival is due to treatment when important characteristics like size have also changed over time."

The study wasn't designed to determine the value of mammograms or treatments, but it implies much about the value of early detection.

"This really helps to show the importance of screening," said Debbie Saslow, who heads breast cancer research at the American Cancer Society. "In addition to finding more small tumors, we're also finding less big tumors."

It actually isn't likely to imply what they want it to about early detection: the sizse may indicate that what we're doing is detecting and treating pseudodisease, which would be why survival rates have improved.

Posted by Orrin Judd at August 9, 2005 12:58 PM
Comments

The main problem with universal screening of anything is that the average person is about as mathematically literate as oj, so critical information such as the rate of false positives and false negatives flies right over their head. And far too many doctors aren't exactly skilled at putting these things into perspective...

The best example of screening being motivated by other than legitimate scientific reasons is the recent arguments for universal HIV testing. The notion that the entire population is at risk from an STD infection is utterly bizarre and fatuous.

Posted by: b at August 9, 2005 1:26 PM

It's bigger than that--the point is that it could be a true positive and still skew the numbers.

Posted by: oj at August 9, 2005 1:36 PM

Of course it is true that given a positive test, even after confirming it with follow-up tests, one still must figure out what the heck it means. But to give you an idea of what I was talking about--when my wife was pregnant with our first child, the test for Down's syndrome came back with an elevated risk, something like 1 chance in several thousand if I recall correctly (and this number purely comes from trying to figure out where in the distribution of certain maternal hormones Down's syndrome occurs--it's not even a real test, more like a probabilistic guess). The doctor then suggests an amnio to confirm the test. An amnio has something like a 1 in a couple hundred chance of inducing miscarriage. Taking such an action under those circumstances is utterly insane.

Posted by: b at August 9, 2005 1:47 PM

Much of the testing for the Medicare population is being done for financial, not medical reasons. Many seniors are in HMOs and they will have every test conceivable that Medicare will pay for.

The HMO my ninety year old mother belonged to had her scheduled for a colonoscopy even though she had no symptoms and when I asked what the treatment would be if some irregularity was found, the doctor had the good grace to tell that there would be no treatment at her age.

We lost no time switching her out of the HMO.

Posted by: erp at August 9, 2005 4:44 PM
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