In a scan, darkly
Every so often I browse through old patient records and before committing them to the shredder I read through the histories they contain. These visits to the past are useful and edifying, allowing a more detached consideration of the events. Has something changed in medical knowledge since then? Do the diagnosis and decisions stand the test of time and added experience? Do I detect any flaws or even serious errors of judgment? Are there lessons to be learned for the future?
During one such recent foray I stopped at a case that provided food for thought. A forty-three-year-old woman who had never smoked, had a clear medical history and no symptoms at all, had gone for a lung CT scan on her own initiative. From a purely scientific point of view there was no reason for a scan, but unexpectedly it showed a tumor in the right lung with a full complement of lymph nodes and multiple metastatic nodules in both lungs. Biopsies showed a poorly differentiated squamous carcinoma, a tumor usually associated with heavy smoking. The diagnosis was established, the tumor was inoperable, and the patient had already started chemotherapy in the local hospital. Medically speaking there was nothing to add: the patient had a difficult disease with an uncertain prognosis, and I never saw her again (she had only come to me for a second opinion).
This history made me think: how much can we rely on our clinical judgment or on official guidelines when cases like this occur outside of our statistical confidence intervals? “Experience is fallible, judgment is difficult” according to the first aphorism of Hippocrates, always to be borne in mind as an antidote to the arrogance fostered by expert diagnostic algorithms and survival statistics.
But suppose the same patient had asked me to authorize a CT scan, and I had refused on the basis of good medical practice and the existing guidelines. If, despite my arguments, she had gone on to have the scan with its resultant findings, how solid would my defence be in a claims court?
So, are we to perform CT scans with no evidence, on demand or indiscriminately, for fear of the worst? If we adopt such a practice, for each true positive finding (as the one described above) there will be scores of ‘spots’ or ‘shadows’ that will generate concern, panic, and insecurity in both patient and doctor. Each one of them will lead to further unnecessary diagnostic studies and interventions, even to surgery, or at best recurrent scans with their associated irradiation, burdening the health budget with thousands of dollars before the ‘spot’ is proclaimed innocent. Surely such wasteful and inappropriate actions cannot be termed good medical practice.
But what about the true-positives? The patient in question had advanced cancer and even with the best medical care would have gained only a few months of survival. One may argue: “What if the tumor have been found earlier?” A couple of years earlier the patient had a normal chest film; would the decision process have been different?
It is obvious that our grasp of diseases, even those that have been extensively studied, is inadequate. What we call “knowledge” is mostly a huge mount of information which forms a still incomplete puzzle. “Mount of information” does not equal “knowledge.” The practice of medicine has (and will continue to have) its own “principle of uncertainty”: Fallible doctors deal with complex patients, and the outcome of these encounters is fraught with uncertainty and expressed as statistical probability. Our experience may expand and our judgment may sharpen with time, but will still remain imperfect. Even with our best scans, we see “in a glass, darkly.” Contrary to what happens in pure mathematics, in medicine one plus one rarely equals just two. If we accept this simple fact, we will have made a small but significant step towards becoming better, humbler, and more humane physicians.
ANTHONY PAPAGIANNIS, MD, MRCP(UK), DipPallMed, FCCP Respiratory Physician. A practicing pulmonologist in Thessaloniki, Greece. He graduated from the Aristotle University of Thessaloniki Medical School. He trained in Internal Medicine in Greece and subsequently in the United Kingdom, and specialized in Pulmonary Medicine. He is a postgraduate instructor in palliative medicine in the University of Thessaly, Larissa, Greece, and also edits the journal of the Thessaloniki Medical Association.