Study reveals inaccuracies in studies of cancer...(k of death from prostate cancer than men...),Health

Dr. Giordano and her team next re-analyzed data from a previously published study of more than 43,000 men with localized prostate cancer who were treated compared with men who were not treated. Like the original study, the researchers analysis revealed that men who were treated for prostate cancer experienced lower mortality rates. However, they also found that in many cases, the cause of death was due to something other than prostate cancer, such as diabetes or pneumonia.

Finally, the investigators re-analyzed data from a previously published study on the effects of fluorouracil-based chemotherapy for colon cancer. They came to the same conclusion as the original research studythat chemotherapy for node positive colon cancer is associated with improved survival. However, they found that the link between the treatment and survival was strongest for non-cancer deaths, which presumably are not related.

The authors attributed the improbable results found in their three analyses to selection biases when patients are treated. For example, selection bias occurs when patients with poorer prognoses are more likely to receive a more efficacious drug, or when patients with better underlying health are more likely to receive a more toxic treatment because they are more likely to tolerate it.

The authors concluded that their findings suggest that the results of observational studies of treatment outcomes should be viewed with caution. They recommended that analyses of observational data should at a minimum attempt to segregate patient outcomes into those that could possibly be due to the treatments vs. those that could not. Many observational studies on cancer treatments only report death rates from all causes and do not specify cancer-related deaths.

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