ABSTRACT
A woman in her fifties complains of meno-and metrorrhagia, and a subsequent biopsy confirms endometrial cancer. Her attending physician suggests a hysterectomy, and other treatments, as needed. The patient may ask: ‘Doctor, is this operation absolutely necessary? What would happen to me if I decided not to have an operation?…How beneficial will this operation be?…Will it stop my bleeding?…What other problems might the operation cause?…Is my disease serious? How probable is it that I will die from it?…How probable is it that I might die on the operating table?…What other treatments can I expect?…’ In many cultures around the world, where the patient's attitude is generally fatalistic, these questions would not be asked and the physician accepting these questions could be perceived as incompetent. The patient might say, ‘Doctor, you are the specialist, you are university-trained, I pay you to decide for me, you must know…’ Elsewhere, an intelligent and curious patient will demand intelligent and competent answers since he or she expects the best possible estimation of his(her) chances and not a guess or an impression. Making a prognosis is another example of a logical discourse whose validity relies heavily on the best evidence available. For example, bronchial cancer is diagnosed in a fifty-year-old male patient who has been
smoking since his teens:
Astute readers will note right away that two of several valid premises are available. Each premise is supported by extensive etiological research (premise A) and survival studies (premise B). Is conclusion C a natural corollary of premises A and B, which are supposed to support and lead to that conclusion? Conclusions in this example do not follow from other, equally solid evidence that tobacco smoking is not only a predominant etiological (risk) factor of bronchial cancer, but also a prognostic one. Are there studies, particularly clinical trials, which show that if lung cancer patients stop smoking, their life expectancies will increase? Or does quitting smoking merely offer a chance to improve some symptoms? Neither focus, nor premises or evidence, are interchangeable. (Not only do they not ‘travel well’, they do not travel at all!) This explains why logical discourse and supporting evidence are more challenging in the area of prognosis than in the area of risk. Current experience is still, in general, much richer in the area of risk than in that of prognosis.
