Do Not Assume What I, or Anyone Else, Assumes

Decorated New York Times Science reporter Gina Kolata recently reported on a  large (100,000 women over 20 years) study published in JAMA Oncology on ductal carcinoma in situ (“DCIS”), a form of abnormal cells found in the milk ducts of breast tissue.  Some medical experts call DCIS stage 0 breast cancer.  Other medical experts do not even consider DCIS to be cancer.  Kolata’s article and the study on which it reports illustrates a problem with viewing medicine as a static field to which fixed assumptions apply:  the human body is a dynamical system that is unpredictable and confounds assumptions.    

Cancer is a particularly good example of the problems with making fixed assumptions about disease.  As Kolata notes:

Over the years, investigators have come to conclude that the old model of cancer – that a few aberrant cells will grow, spread and inevitably become a deadly cancer if not destroyed – is wrong.  Small clumps of abnormal cells may just stop growing, scientists now know.  Even invasive cancers do not always grow.  Some regress or disappear.  That is especially true in prostate cancer, where as many as half of all cancers found with screening will not progress is they are simply left alone.  But it also seems true in breast cancer, researchers say.

Doctors used to assume that DCIS was an incipient form of cancer that, if not treated, would grow into a tumor and eventually metastasize.  The use of mammograms greatly increased the diagnosis of DCIS, which led to greatly increased treatment of it.  Early on, mastectomy was the preferred method of treatment.  The reason was based on applying the rules of a different cancer to DCIS.  Studies had demonstrated that excising early neoplastic lesions on the cervix that were discovered in Pap tests prevented deaths from cervical cancer; hence, doctors reasoned that cutting out DCIS lesions would prevent deaths from breast cancer.  As lumpectomy became an accepted alternate treatment to mastectomy in breast cancer, doctors began treating DCIS with lumpectomy also.  The problem is that the JAMA study found there was no difference in the death rate from breast cancer of women diagnosed with DCIS (regardless of the form of treatment they received or whether they received no treatment) and the death rate from breast cancer in the general population of women.  The study also found that despite aggressively treating DCIS, there was no impact on the incidence of invasive breast cancer in the general population.  This would not be expected:  “if treating DCIS was supposed to fend off invasive breast cancer, the incidence of invasive breast cancer should have plummeted once DCIS was being found and treated.”

The JAMA Oncology study can teach those of us in the medico-legal world a valuable lesson about the perils of making assumptions without testing them.  In the medico-legal world, we need to pay attention to the evidence around us and to the impact the evidence has on the claim, especially impacts that are unexpected or run counter to our assumptions about the claim.  Failure to do so will inevitably result in error. 

The DCIS case is instructive.  Surgeons began performing mastectomies and later lumpectomies to treat DCIS with the rise of mammogram screening.  They did so on the advice of oncologists and gynecologists who assumed that the abnormal cells of DCIS were like the abnormal cervix cells found on Pap tests. Despite growing evidence that certain neoplasms do not metastasize and that different cancers behave and respond to treatment differently, oncologists and gynecologists kept recommending that DCIS be excised (and general surgeons dutifully performed the excisions).  And even after years of excision being standard treatment for DCIS, no one bothered to gauge whether the treatment in fact lowered death rates from breast cancer because the medical community did not question the assumption that DCIS would lead to breast cancer if not excised.  The assumption, based on an analogy instead of medical evidence, was so deeply embedded in the medical profession that few practitioners thought to question it.  As a result, thousands and thousands of unnecessary mastectomies and lumpectomies were performed over the last three decades which caused physical injury, physical pain, psychological distress (not to mention massive medical costs), and did not prevent breast cancer.  And all of this was caused by a failure to pay attention to the actual evidence accruing and instead relying on an untested assumption.

DCIS offers a sobering example of why we cannot rest our claims analyses on untested assumptions.  Instead, we must constantly test our assumptions against the available evidence to determine whether the inferences drawn therefrom support the assumptions.  While the assumptions made in individual claims are not likely to have as deleterious consequences as the assumptions the medical community made about DCIS, they can have a negative impact on our ability to resolve claims efficiently and effectively.  And if the assumptions are repeated over time, the skewed results we achieve in resolving claims could have a significant negative monetary impact in the aggregate.  Instead, we should constantly be testing our assumptions against the actual evidence; further, we should be prepared to abandon our assumptions if the available evidence does not support them.  Claims are not static but rather change over time as they are developed and new evidence is obtained.  To manage claims effectively, we must adapt to those changes and develop a strategy that is responsive to them.  If we do so we will not be surprised when the unexpected arises and we will respond to it nimbly.  We will also avoid the pitfall of untested assumptions that, like was the case with DCIS, can cause us to pursue strategies that may not only be ineffective but also harmful.  

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