It seems our society lives in dread of cancer, one word that is the purgatory of the modern western world. How often does a patient reply, when you tell them the positive results of an investigation, “Thank heavens it isn’t cancer” even though the actual diagnosis may be more life threatening than many neoplasia. The almost biblical belief system behind the word cancer comes with a corollary that poses a major problem to effective rational health care, namely the “must get it out” association. That medical school surgical dictum “When in doubt, cut it out” may have been superseded by more politically correct phrases, but the thought remains ensconced in our own and our patients’ minds when faced with a diagnosis of a solid neoplasia.
But why is this so? Why do we believe that a diagnosis based on visualisation of some cells down a microscope has a 100% positive predictive value, especially when the patient has absolutely no symptoms or clinical signs to support the diagnosis? Have you ever tried to explain the gap between a histological and a clinical diagnosis to a patient?
Not easy, yet we know from the prostate screening studies that a histological diagnosis of prostatic carcinoma is poorly predictive of subsequent death from that cancer. Try the melanoma studies demonstrating a significant interoperator variability in histology results. What about the phenomenon of diagnostic drift, especially the recent study showing that, in current day reviewing of skin biopsy slides diagnosed as normal in the 1990s, a significant number were found to be low grade superficial spreading melanoma. Little wonder we are removing more melanomas than ever before.
What we really need is a change of thinking, more focused on a “cancer” diagnosis based on metastatic disease potential (ignoring the problems caused by primary tumour enlargement, but remember that this includes plenty of non malignant growths). This requires a different diagnostic method and is the likely way things will move in cancer diagnosis. Consider if we had a test for prostate cancer that had a better predictive ability for the development of metastatic or local spread disease. Same for breast cancers, especially the very problematical DCIS.
Sentinel node biopsy seems to have potential, at least in terms of identifying if metastasis has already occurred, but greater potential is likely to lie in biochemical indicators of metastatic activity and potential, such as have already been found in inflammatory breast cancer. It’s unlikely imaging as we know it will be a suitable answer, but perhaps, in conjunction with metastatic markers, we may be able in the future to reassure patients that their cancer is better lived with, rather than without.
Our challenge will be to shift this cancer belief system and the associated concepts of appropriate therapy.
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