Colon cancer screening (fecal occult blood screening) does NOT reduce death rate over 30 years

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Saturday, May 02, 2015 1:06 pm Email this article

Screening for colon cancer (fecal occult-blood testing), either every year or every other year, did NOT reduce the total risk of death after a 30 year followup according to a recent analysis of the Minnesota Colon Cancer Control Study.

The percentage of people who had died from any cause after a 30-year follow-up was exactly the same in each group (71% of people had died in each group).

• 71% of people had died in those screened for colon cancer every year for 11 years
• 71% of people had died in those screened for colon cancer every other year, a total of 6 times
• 71% of people had died in those who were NOT screened for colon cancer

Prof. H. Gilbert Welch, MD writes about this in his most recent book Less Medicine, More Health: 7 Assumptions That Drive Too Much Medical Care.

He is also the author of the wonderful book Overdiagnosed: Making People Sick In Pursuit Of Health which is about the same topic as this book, the topic of over-diagnosis and over-treatment which does NOT help people live longer.

The reason that I feel passionately about this is because my mother suffered tragically from drug-induced side effects which her doctors were blind to.

It is along the same lines as Prof. Welch’s books which look at the effects of of over-diagnosis and over-treatment.

Screening for colon cancer does NOT reduce the total risk of death

Conclusion: Screening for colon cancer by looking for fecal occult blood testing, does NOT reduce all-cause mortality

“Through 30 years of follow-up… No reduction was observed in all-cause mortality…” they note in the study.

“The effect of screening with fecal occult-blood testing on colorectal-cancer mortality persists after 30 years

but does not influence all-cause mortality,”

the paper concludes.

“In conclusion, there is… no observable reduction in all-cause mortality…” the authors conclude.

Prof. H. Gilbert Welch, MD comments about this study

Prof. H. Gilbert Welch, MD comments from his book book Less Medicine, More Health: 7 Assumptions That Drive Too Much Medical Care

(It is from Chapter 3 / Assumption #3: Sooner Is Always Better: Disturbing truth: Early diagnosis can needlessly turn people into patients, under the section titled “Does Screening Save Lives?”)

“The distinction between cancer deaths and all deaths was highlighted in a recent long-term follow-up of the Minnesota Colon Cancer Control Study—another herculean study of roughly 50,000 people followed for fifteen years,” Prof. H. Gilbert Welch, MD writes in his book book Less Medicine, More Health: 7 Assumptions That Drive Too Much Medical Care.

“The study was not investigating screening colonoscopy; it was investigating screening for fecal occult blood (a simple test for blood in the stool—often referred to as “stool cards”).

“Its findings were published in 1993: annual screening reduced colon cancer mortality by 33 percent.

“It is one of the most influential randomized trials of screening.

“It’s a classic.

“In 2013, the investigators published a long-term follow-up: thirty years following the initiation of screening.

“By now, most of the participants had died; they were between ages fifty and eighty at the start of the study.

“In the group that wasn’t screened, 3 percent died from colon cancer.

“In the screened group, 2 percent died from colon cancer,” Prof. H. Gilbert Welch, MD writes.

“In other words, screening reduced the rate of colon cancer death by one-third—that’s the 33 percent reduction.

“There is a nice graph showing the effect over time.

“The vertical axis shows the proportion dying from colon cancer, the horizontal axis shows the time from the start of the study: from zero to thirty years.

“The curve for both groups rises over time as more people die from colon cancer.

“So even in the screened group, people died from colon cancer.

“Again, that’s the birds.

“But the curve for the screened group rises more slowly than does the curve for those not screened.

“At the end of thirty years, the curves end at 2 percent and 3 percent.

“That’s the effect of catching rabbits; that’s the benefit of screening.

“But there was also a second graph.

“It too depicted death over time, but in this case it showed the proportion dying for any reason—overall mortality.

“The curves for the screened group and the not-screened group are right on top of each other.

“In fact, it just looks like one curve.

“That means the overall rate of death was exactly the same,” Prof. H. Gilbert Welch, MD continues.

“Each year the proportion who died was the same for both groups.

“At the end of thirty years, the curves end at 71 percent and 71 percent.

“Screening didn’t help people live longer.

“Not even a little bit.

“How can that be?

“Two possible explanations exist: optimistic and pessimistic.

“The optimistic explanation is chance.

“While one might expect the overall death curves to end at 70 percent for screening and 71 percent for those not screened—to reflect that 1 percent difference in colon cancer death—by chance it didn’t happen that way.

“The pessimistic explanation is that while screening lowered the rate of death from colon cancer, it also increased the rate of death from other causes.

“A lot happened to the screening group (tests, procedures, and so on) and a lot of it happened to those not destined to die from colon cancer.

“Remember: screening must involve many, to potentially help a few.

“A tiny increase in death among the many could wipe out the larger benefit to the few,” Prof. H. Gilbert Welch, MD concludes.

Reference

Shaukat A, Mongin SJ, Geisser MS, Lederle FA, Bond JH, Mandel JS, and Church TR. Long-term mortality after screening for colorectal cancer. N Engl J Med, 2013 Sep 19; 369(12): 1106-1114.

The published paper about this study is available for free here.

Author’s Contact Info

Aasma Shaukat, MD, MPH
1 Veterans Dr, 111-D
Minneapolis, MN 55417 USA
.(JavaScript must be enabled to view this email address)

Reference

Welch HG. Less Medicine, More Health: 7 Assumptions That Drive Too Much Medical Care. 2015-03-03; 240 pages.

Author’s Contact Info

H. Gilbert Welch, MD
Dartmouth Institute for Health Policy and Clinical Practice
Dartmouth College
Hanover, New Hampshire 03766, USA
.(JavaScript must be enabled to view this email address)
(603) 653-0836 phone

Articles on the same subject can be found here:

• Cancer

• Cancer screening (Does it do any good?)

• Cancer, Colorectal

• Doctor - H. Gilbert Welch, MD (author of Overdiagnosed and Less Medicine, More Health)