Screening for Prevention vs. Early Detection | Response to JAMA Article

The July 29, 2013 edition of the Journal of the American Medical Association (JAMA) includes an opinion piece titled, “Over diagnoses and treatment of cancer? An opportunity for improvement.”  The authors highlight the growing body of literature and a growing depth of understanding as it relates to cancer prevention and early detection.

They call for an open dialogue between patients and the medical community. Fight Colorectal Cancer couldn’t resist weighing in on this issue.

Colorectal cancer is a “Crown Jewel” of cancer screening

The article (which can be read in full here) discusses what we’ve learned from data about cancer incidence (number of diagnoses) and cancer mortality (number of deaths).  Interestingly, colorectal cancer and cervical cancer are seen as the ‘crown jewels’ of screening because screening has led to:

  • Removal of pre-cancerous tissue (e.g., polyps)
  • Detection of early disease
  • Fewer cases of late-stage disease

So screening for cervical and colorectal cancer rocks because screening increases the number of cancers prevented and found early when treatment cures patients. And, it decreases the number of cancers found late when treatment is rarely curative.

In contrast, increased screening for other forms of cancer has increased the number of diagnoses, but it’s not clear the number of deaths is decreasing in the same way.  The article states:

Barrett’s esophagus and ductal carcinoma of the breast are examples for which the detection and removal of lesions considered precancerous have not led to lower incidence of invasive cancer.”

In other words, even though screening and early detection has increased, the number of deaths due to cancer hasn’t dropped proportionately.

Discussing the potential harms of cancer screening

This seems counter-intuitive to us – if you remove pre-cancerous tissue, aren’t you decreasing the number of cases of cancer?

The article makes that case that there are different types of pre-cancer, including types which probably won’t progress, or will progress very slowly. In that situation, the “watch and wait” strategy may be more appropriate than treatment – because all treatment has side effects.

For example, The US Preventive Services Task Force has recommended against routine screening for prostate cancer via PSA testing because they felt the data showed the risks of early detection are greater than potential benefit.   Even a biopsy for prostate cancer based on a PSA test can cause problems, and treatment for very early stage prostate cancer results in a significant number of long-term side effects such as erectile dysfunction and incontinence.

The authors make the case that diagnoses of slow-growing or “indolent” cancer should not be called or counted as “cancer.”  They make several other recommendations, including a call for research that will help identify which pre-cancerous tissue is likely to progress to cancer.  And they urge patients and their doctors to have discussions about the potential harms of screening.

 The opportunity for colorectal cancer in the cancer screening debate

This is a complex issue, and will undoubtedly lead to a public debate about cancer screening in general.  In the case of colorectal cancer screening, there is a clear opportunity.

We can catch this cancer early and we can remove it before it starts.  Screening works. We need better screening options –- wouldn’t a $5 blood test that was as accurate as a colonoscopy be great?

And since no screening test will ever be 100% accurate, we need to continue to fight for a cure and support research to find better ways to treat colorectal cancer.

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