Ecologic Fallacy and Cancer in Africa

Ecologic Fallacy and Cancer in Africa

Clement Adebayo Adebamowo, MD, ScD

Dec 20, 2010

This is not about global warming—- ;-) ! But how many times have you thought about ecologic fallacy? Not many of us think about it and would wonder what it has to do with cancer care. This problem has been on my mind for years as I have watched cancer patients and health care professionals struggle with the difference between their real-life experience of individual patients and the result of medical research literature.

Because cancer does not have one “cause,” literature is replete with risk factors for cancers. For example, breast cancer has been consistently associated with early onset of menarche, late onset of menopause, low and nulliparity, late age at first full-term pregnancy and high total lifetime breastfeeding duration. Yet many cancer care professionals, patients, and patients’ relatives have often wondered why their experience is so different from this litany of risk factors.

Many times, the individual patient with breast cancer in Africa is young, multiparous, has had late age at onset of menarche, and has had high total lifetime duration of breastfeeding. This causes great distress because apparently the patient’s profile does not fit that of someone “who should have cancer.” This distress derives directly from drawing conclusions about individuals—in this case, patients with breast cancer—from aggregate—in this case, epidemiology—data.
So next time you see patients whose characteristics do not fit that of the general population of individuals with that kind of cancer, think about ecological fallacy and remember that this one case does not make a difference. There will always be patients in the tails of the distribution whose characteristics are different from that of the majority of patients and this should not lead us to erroneous conclusions.

Now, having said this, such outliers may, in some circumstances, be informative. They may represent a different pattern of disease with different etiology, requiring different treatments and having different outcome. How can one tell which of the aberrant presentations is an interesting phenomenon and which is not? Now that is where the challenge lies.


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George W. Sledge, MD, FASCO

Dec, 20 2010 11:44 AM

Clement's point on the importance of outliers is well taken.  An old saying in science is "cherish your exceptions." This is particularly true as we move from the "one size fits all" model of cancer to the realization that many human cancers are families of diseases that happen to share the same organ, with distinctive biology and therefore special therapeutics.

Doug H.M. Pyle, MBA

Dec, 23 2010 9:10 AM

This is a really interesting point.  Clement refers to individuals who appear to be on the tail of a distribution.  To take this a step further, and this may be what he and George are alluding to, what if the reality is that the distributions for population subsets are significantly different from one another, so an individual may appear to be in the tail of one "global" distribution for that disease, but if we had more data on that individual's subset population we would find that they were closer to the center for their subset distribution.  And what impact would that knowledge have on what we do from a global health/cancer control perspective?  How do we take advantage of our increasing awareness of each disease's complexity and variability across multiple dimensions and not be paralyzed by it?  Mass action doesn't like complexity.

George W. Sledge, MD, FASCO

Dec, 23 2010 11:06 AM

To Doug's point, we are already seeing this, an example being the differences in response to EGFR inhibition, with Asian women having significantly higher response rates.  I suspect there are many genomic nooks and crannies out there waiting to be found.  Because historically most clinical cancer research was performed in Western populations, it would not surprise you if we have missed some things, both positive and negative, in new drug development that is population- and sub-population-based.

Francis Sajo YAGARGA

Dec, 26 2010 5:55 PM

Well done Prof Clement.Mass action in all corners especially in our localities must be done in all areas of cancers.

L. Michael Glode, MD, FACP, FASCO

Dec, 28 2010 10:18 PM

 This is an excellent discussion - the "experiments of nature" always have much to teach us. But of course so does the macro view. Especially for those of us who are statistically challenged, I found this highly watched video on world health progress to be both informative and hopeful.

Daniel A. Vorobiof, MD

Jan, 18 2011 2:09 PM

 I have just read Clement's blog and I must say that after 30 years of being a medical oncologist, I couldn't agree more with his comments. What Clement calls "ecologic fallacy" was always , in my understanding, a major epidemiological deception. We learn many things but when we apply them to our daily practices, they are completely different and do not always "fit the pattern". Our patients (and their cancers) don't read medical books ! And life in Africa is really different, so extrapolations never work for the benefit of those that require a different handling and a specific tailored approach. 

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