Origin And Locality Of Carcinoma

In regard to their place of origin it may be said that cancers always arise where epithelium or endothelium is normally present, and there seems no doubt that the epithelium of the cancer takes origin in the similar cells of the normal tissue.

Virchow, although distinguishing sarcoma from cancer as a connective tissue tumour, asserted that the cancerous tissue takes origin in connective tissue. The great authority of Virchow has caused this view to be perpetuated more than it otherwise would have been. It was controverted first by Thiersch, who showed that in epithelial cancer the cells can be seen to originate from the epidermic cells. Waldeyer, in a series of very elaborate papers, went over most of the seats of cancer, and showed that in these the cancerous tissue is directly derived from the existing epithelium.

In many situations the actual Connection with the existing epithelial structures can be traced, especially if the growing edge of the carcinoma be examined. Thus in a section of an epithelioma of the skin, or of the lip or tongue, the cylinders of epithelium which form the essential constituents of the tumour, can be often traced into direct connection with the Malpighian layer of the epidermis. <See Fig. 105.) Again, in some cases of primary cancer of the kidney it can be seen that the tumour is arising by direct transformation of the kidney tissue. The primary cancer of the kidney is in many cases not a tumour added on to the kidney, but it is generally a portion of, or sometimes the whole kidney, which has undergone an enormous enlargement while keeping its general shape; it is in fact the kidney or portion of kidney transformed. And when we examine the marginal parts of such a tumour we find the epithelium of the uriniferous tubules in an active state of proliferation, the tubules getting distended with new-formed epithelium. The epithelium also, in its state of activity, is altering its shape according to the mutual pressure of the cells, so that it sometimes gets elongated and tailed. (See Fig. 1.06).

This activity of the normal epithelium seems to be the regular preliminary to the cancerous formation where it takes origin in glands. In the mamma, for example, there are some cancers in which the tumours have a special connection with the ducts (Duct-cancer; often coexisting with eczema of the nipple and areola). In these the epithelium of the ducts, from the nipple downwards, shows great activity, so that the ducts become distended with epithelium, which in accumulating loses its normal cylindrical form. The epithelium of the acini of the gland also partakes in the active new-formation. Similar processes have been observed in cancer of the uterus and elsewhere. We may therefore conclude that the first stage in the formation of a cancer is an abnormal activity in the epithelium of a particular locality.

Epithelioma. Edge of tumour showing connection of the ingrowing epithelium with the normal epidermis, x 45.

Fig. 105. - Epithelioma. Edge of tumour showing connection of the ingrowing epithelium with the normal epidermis, x 45.

From a cancer of the kidney.

Fig. 106. - From a cancer of the kidney. A tubule is represented in which the epithelium is undergoing alterations in shape, x 300.

The next stage in the development of the cancer is that its epithelial elements break bounds and extend out into the surrounding tissue. It is this atypical extension which is the most characteristic feature.

As already indicated, cancer may originate in any locality where epithelium or endothelium is normally present. It occurs in the skin and mucous membranes, in glands, in the lungs, in the brain, and (very rarely) on serous membranes. But it shows great preferences for certain localities. Thus the preeminent seats of cancer are the lower lip, tongue, mamma, uterus, and stomach. Many of these preferences can he accounted for by local peculiarities. Cancer of the lower lip and tongue have been ascribed to the irritation of short or rough tobacco-pipes and the jagged edges of carious teeth. The mamma and uterus suffer involution before other organs of the body, and as cancer is a disease of advanced life, the earlier decadence of these organs may determine the frequency of the occurrence of cancer in them. Again, exposure to injury and friction have been already alluded to as determining the localities of cancers.

The connection of cancer with irritation of the epithelial structures is forcibly shown in cases of cancer occurring in chimney-sweepers or workers in paraffin-refineries. In the latter case there are in the skin, apart from the cancerous growth, numerous elevations of the epidermis, of one of which Fig. 107 is a reproduction, indicating that the irritant has acted on the epidermis in a special manner.

Section of skin from neighbourhood of a cancer in a paraffin worker.

Fig. 107. - Section of skin from neighbourhood of a cancer in a paraffin worker. There is a striking hypertrophy of the epidermis producing a warty condition. xl2.

Age and sex have important influences on the origin and locality of cancer. It is almost unknown during infancy and childhood, and is very rare under thirty years of age. It is frequent from thirty-five till seventy-five. After this age it becomes less frequent, and is rare in extreme old age. It seems strange that a disease characterized by undue activity of growth of certain elements should occur especially when the body generally is losing in vigour. An explanation of this was suggested by Thiersch, to the effect that, as cancer consists essentially in an exaggerated growth of epithelium,'which invades the neighbouring structures, especially the connective tissue, the cause may lie rather in a falling away of the resistance of the other tissues than an extra vigour of the epithelium. The occurrence of cancers in old cicatrices, which consist of a very imperfect connective tissue, would lend some force to this view. The liability of the mamma and uterus to cancer causes a considerable preponderance in the female sex, ■which is only partly redressed by the frequency of cancer of the tongue, lip, and oesophagus in the male.

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