Screening Doesn’t Explain All Colorectal Cancer Drop

LEBANON, NH — Colorectal-cancer incidence among U.S. adults 50 or older has dropped by almost 40% since 1975 and by more than 45% since its peak in the mid-1980s.

That’s according to perspective piece in the New England Journal of Medicine which also points out that colorectal-cancer mortality has fallen by more than half.1

While the obvious answer might point to effective screening, authors from the VA Outcomes Group at the White River Junction, VT, VAMC, and the Dartmouth Institute for Health Policy and Clinical Practice suggest more must be involved.

These trends are often attributed to screening, but the magnitude of the changes alone suggests that other factors must be involved.

“None of the trials of colorectal-cancer screening has shown a 50% reduction in mortality — nor have trials of screening for any type of cancer,” write H. Gilbert Welch, MD, MPH, and Douglas J. Robertson, MD, MPH.

So what explains the decrease in colorectal-cancer mortality?

Welch and Robertson suggest that has to do with improved treatment and better surgical techniques and care; the earlier detection of symptomatic disease and subsequent reductions in mortality that occur even in the absence of widespread screening and that “there could be fewer cases of colorectal cancer occurring in the first place.”

The authors suggest that might have occurred because of changes in diet among Americans, alteration of gut flora through use of therapies such as antibiotics and that commonly-used medications, such as aspirin, are shown to reduce colorectal neoplasia.

1 Welch HG, Robertson DJ. Colorectal Cancer on the Decline — Why Screening Can’t Explain It All. N Engl J Med. 2016 Apr 28;374(17):1605-7. doi:10.1056/NEJMp1600448. PubMed PMID: 27119236.

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