In the past here in this blog, I and others have discussed the problem with the nomenclature of in-situ carcinoma, particularly with regard to breast carcinoma. The problems relate both to the difficulty in distinguishing DCIS from atypical hyperplasia, and the fact that the term "carcinoma in situ" applies the "C word" to a lesion that is, in its current state, incapable of acting in a fully malignant fashion. As we noted, in other organ systems, notably the GYN tract, pathologists and gynecologists have gotten away from this problem by switching to the intraepithelial neoplasia terminology.
In the prostate gland, there are similar but not identical problems. The in-situ carcinoma in the prostate has long been labeled with the intraepithelial neoplasia rubric, ie. high-grade prostatic intraepithelial neoplasia" (HGPIN). In fact the term, "carcinoma in-situ" has never been used to any significant degree in this organ. Moreover, since its initial description, the frequency of HGPIN in biopsy specimens has increased markedly with increasing recognition of this lesion, and its biologic significance has correspondingly decreased. As we all know, it is quite common in needle biopsies from older males, and even some younger ones. It's presence as an isolated finding does not typically lead to any definitive therapy. So in respect to in-situ disease, our terminology and approach to the prostate, it can be argued, is appropriate and reality based.
However, the major problems with regard to invasive prostatic carcinoma are, 1. that it is an incredibly prevalent disease that in many instances remains indolent throughout the patient's life, and 2. with the advent of immunohistochemical staining for basal epithelial markers and racemase, we can now detect small 3-5 gland foci of "carcinoma" that would never have been diagnosed as such even a decade ago. These small foci of well-differentiated carcinoma are invasive lesions so the "intraepithelial neoplasia" system isn't at all appropriate. Nonetheless, most of them will do nothing, yet the patient is labelled as having cancer. Many folks, both patients and clinicians have a problem with the concept of clinically irrelevant "cancer." As our former chair of urology used to say, "saying you have a little bit of cancer is like saying you're a little bit pregnant."
Recently, the NIH convened a consensus panel, which concluded that "active surveillance" is an appropriate course of action for men with low-grade and low-stage prostatic carcinoma. This is a welcome and many would argue overdue decision. It gives clinicians who elect to follow their patients with these small lesions important additional support for that decision. The remaining problem, of course, is to get patients to understand that doing nothing for carcinoma is a rational decision. The NIH consensus panel also recognized this problem and suggested that it may well be a mistake to call these low-grade, low-volume lesion "cancer," as this may lead to unnecessary patient anxiety and prompt patients to push for unnecessary treatment.
In a recent editorial in the February issue of The Oncologist
entitled, "Call it Cancer," Drs. Bruce Chamner and Matthew Smith from MGH argue for retaining the cancer designation. Their arguments are well constructed and well reasoned, but they do not deal with the fact that the minimum threshold for the diagnosis of prostate cancer in 2012 is not the same as it was in, for example, 1990. Today, that diagnosis may well be based on foci far too small to have been unequivocally diagnosed as carcinoma without the aid of immunohistochemical support that was unavailable until relatively recently. Second, as all pathologists know, prostate cancer is a notably multifocal disease and there is no evidence (nor is there likely to ever be) that such microscopic foci of low-grade carcinoma are themselves the seeds for the development of subsequent, clinically significant cancers. Rather they may simply be markers of limited increased risk.
Unfortunately, the NIH panel did not suggest an alternative terminology for these small foci of "carcinoma" but it is heartening to know that they are well aware of the problem and the need for a better solution. Perhaps these should be called, "glandular neoplasia of low (or uncertain) malignant potential" to borrow again from our gynecologic colleagues.