Friday, March 9, 2012

We all need another math class

We need a math class that explains the importance of statistics - the fact that there is more to statistics than just the number. We always need to look at both sides of the equation.

"What are the harms of this screening test? What are the potential benefits? If the patient gets an answer of increased five-year survival, that's an indication that their doctor doesn't know what they are talking about," Brawley said.

Cancer screenings are lauded as being the most important thing we can do to increase survival rates. Yes they help us find cancers earlier, before they become symptomatic. This is important and we should not skip screenings.

But, and there is always a big fat but(t), the survival rates are not the important numbers. The death rates are more important:

"Doctors were three times more likely to recommend a test that increased the (irrelevant) five-year survival rates from 68 percent to 99 percent than to recommend a test that slashed the much more important death rate from 2 in 1,000 people to 1.6 in 1,000."

Yes this is a tad bit confusing and I had to read the same article three times to figure out what they meant, and I took statistics (but I do have chemo brain so maybe it has countered my education).

"The reason is that screening automatically increases survival rates, because finding a tumor early means people live longer with their cancer diagnosis than if they had waited until they had symptoms to see a doctor -- regardless of whether or not anything is done to treat them. 

In some cases, such as slow-growing prostate cancers, the tumor might never have bothered them in the first place. That means screening, and the further tests and treatments that might follow, would have led to costs and potential side effects without any benefit to the patient -- a phenomenon called overdiagnosis.

"For helping people understand if screening works, survival rates are misleading," said Dr. Steven Woloshin, of Dartmouth Medical School in Hanover, New Hampshire, who worked on the new survey.

He told Reuters Health that death rates gleaned from clinical trials are the only reliable way to judge if a screening test is effective. But organizations that promote screening, such as the breast cancer charity Susan G. Komen for the Cure, tend to prefer survival rates, which sound more impressive."

So we don't want the survival rates, we need to understand the bigger picture - would this cancer ever have been a problem for me? Or would it have taken 30 years to get to be problematic and that is well beyond my life expectancy? Cancer rates increase as people age, so I can see this being important for an older adult. Would it have been a problem for them ever? And the potential side effects from cancer treatment, can cause other cancers and lifelong medical problems.

For now I'll keep with my screenings but will also remember to take the findings with a large grain of salt.

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