Monday, July 29, 2013

Overdiagnosis and Death

A recent focus on the "over diagnosis" of cancer has been highlighted in JAMA and the NY Times. The Times states:

The concern, however, is that since doctors do not yet have a clear way to tell the difference between benign or slow-growing tumors and aggressive diseases with many of these conditions, they treat everything as if it might become aggressive. As a result, doctors are finding and treating scores of seemingly precancerous lesions and early-stage cancers — like ductal carcinoma in situ, a condition called Barrett’s esophagus, small thyroid tumors and early prostate cancer. But even after aggressively treating those conditions for years, there has not been a commensurate reduction in invasive cancer, suggesting that overdiagnosis and overtreatment are occurring on a large scale.

That is a simple way to say that  we know only after the fact what is aggressive and what is indolent and not before the fact. The classic example is prostate cancer. Of course we do not want to treat indolent prostate cancer and of course we do want to treat aggressive prostate cancer. But how do we tell. There are new tests which purport to assit tyhat process but in my opinion in a wek manner.

The JAMA piece states:

An ideal screening intervention focuses on detection of disease that will ultimately cause harm, that is
more likely to be cured if detected early, and for which curative treatments are more effective in early-stage disease. Going forward, the ability to design better screening programs will depend on the ability to better characterize the biology of the disease detected and to use disease dynamics (behavior over time)and molecular diagnostics that determine whether cancer will be aggressive or indolent to avoid over treatment. Understanding the biology of individual cancers is necessary to optimize early detection programs and tailor treatments accordingly. The following recommendations were made to the National Cancer Institute for consideration and dissemination.

Yet we are not there  yet. We understand what genes may cause aggressive disease but we are at a loss of epigenetic characteristics, at least now.

JAMA continues:

The original intent of screening was to detect cancer at the earliest stages to improve outcomes;however,detection of cancers with better biology contributes to better outcomes. Screening always results in identifying more indolent disease. Although non-physician has the intention to over treat or over diagnose cancer, screening and patient awareness have increased the chance of identifying a spectrum of cancers,some of which are not life threatening.Policies that prevent or reduce the chance of over diagnosis and avoid over treatment are needed, while maintaining those gains by which early detection is a major contributor to decreasing mortality and locally advanced disease. The recommendations of the task force are intended as initial approaches. Physicians and patients should engage in open discussion about these complex issues.The media should better understand and communicate the message so that as a community the approach to screening can be improved.

The recommendation should be to better understand what the true tell tale imprints of cancer are. DIC may or may not be bad, HG PIN may also be so, and melanoma in situ may just be a wandering melanocyte. At what point do we jump to attention and attack?