On the frequency of occurrence of occult carcinoma of the prostrate

For a number of years the writer has been impressed by the frequency with which small carcinomata have been found in the prostate in the routine autopsy material of this Department. It seemed that these small tumours, which had attracted no attention clinically and which were brought to light unexpectedly at autopsy, were being encountered much more often than the usual estimates of the frequency of occurrence of prostatic carcinoma would have led on to expect. Impressions formed from unanalysed material are, of course, often misleading, and it was in the attempt to gain more precise information about the matter that the present study was undertaken. This study makes no pretensions to being an elaborate and complete examination of the question. It represents only a very simple and direct study of a limited amount of readily available material, the nature of which was such as to preclude any detailed analysis of various associated problems which suggest themselves. The results of the study are, nevertheless, sufficiently clear-cut and interesting to warrant being set forth in a brief report. It is the practice in this Department to have histological preparations made from each organ of every body that comes to autopsy, regardless of whether the tissue appears normal or abnormal macroscopically, or of whether the clinical history does or does not provide a reason for suspecting the presence of microscopic lesions. Since this procedure involves the preparation of a large number of slides from each autopsy, it is only in the case of a special interest in a particular organ that more than one block is sectioned routinely from a macroscopically normal organ on which the clinical history casts no suspicion, or from one exhibiting only a very common and obvious lesion. In most case, then, there was readily available for the present study only the routine single section of the prostate taken at the time of autopsy. It is important to point out, therefore, that although the frequency with which cancer was found in these sections is surprisingly high, the actual incidence of this condition is, in all probability, still higher; for the tumours with which this article deals are, for the most part, so small and so inconspicuous macroscopically that it was only a matter of chance that the routine section passed through them. Had numerous sections been made through various regions in each prostate there can be little doubt that similar minute early carcinomata would have been found is some of the negative cases in the present series. It must be particularly emphasized that in each instance recorded in this article the growth in question represents a true carcinoma. The writer is well aware that occasional forms of benign hypertrophy may be mistaken for carcinoma; that the prostatic acini may be so distorted by inflammatory lesions as to simulate carcinoma; and that when nodules of hypertrophy are present in a prostate, the previously normal tissue may be so compressed by the expanding nodules as to appear in the form of strands of cells which, when cut at various angles, may simulate strands of tumour cells on casual observation. These confusing conditions however, are readily distinguishable from ‘frank’ carcinoma on careful examination, and in the present series no cases regarded as questionable were included. In each instance, the tumour is composed of plump epithelial cells growing irregularly in strands and in acinar formation, and invading the neighbouring tissue in the manner characteristic of carcinoma. The illustrations are typical of the character of all the tumours in the group. Since most of the tumours in this report represent the very early stages in the development of prostatic cancer, it is regrettable that the material was not of a nature which would have permitted a more satisfactory study of the question of the most common site of origin of the tumours. It is impossible in most cases to determine precisely the level at which the section containing the tumour was taken. However, although the exact level of the sections cannot be determined, it is perfectly clear that there is a decided tendency for the very early tumours to be situated either laterally or posteriorly in the tissue near the capsule of the gland, with the result that the capsule is not infrequently invaded before the prostate itself is appreciably enlarged by the growth of the tumour. In the case of the late tumours involving practically the entire gland it was not possible to determine the co-existence of benign hypertrophy, but in the remainder of the cases, hypertrophy was present in addition to the carcinoma in 70%. When the tumours are very small, i.e. before widespread invasion has occurred, they are often situated either in normal tissue or in the glandular tissue which is compressed by nodules of hypertrophy. That cancer may arise also within the newly formed tissue of a nodule of hypertrophy there is no doubt, but the situation of the early tumours comprising the present series suggests that the non-hypertrophied senile tissue and the compressed atrophic glands outside the expanding nodules of hypertrophy are, perhaps, favourite sites of origin. * Presented to American Urological Association (Clinical Meeting), Baltimore, May 25, 1934. Reprinted from The Journal of Urology, 33:3, 1935 with permission from the American Urological Association. Department of Pathology, The Johns Hopkins Medical School, Baltimore, MD, USA. Published by Oxford University Press on behalf of the International Epidemiological Association The Author 2007; all rights reserved. Advance Access publication 17 April 2007 International Journal of Epidemiology 2007;36:274–277 doi:10.1093/ije/dym050