There are two quite different types of cancer that affect kidney. The of the two is known as transitional-cell papillomatosis, a type of tumor that may arise anywhere in the special endothelial lining of the kidney, ureter, or bladder .
If the disease is still confined to one kidney, the treatment of kidney cancer is by the surgical removal of that kidney, but this form of malignancy tends to be multifocal; that is, similar tumors tend to appear elsewhere throughout the urinary collecting system.
The common kidney cancer is an adenocarcinoma, also known by its traditional name hypernephroma. While every variant is possible, kidney cancer tends to be a cancer of moderate growth rate and to be a disease of the middle aged and elderly.
In the human no causative factors have yet been identified, but identical tumors can be produced in some experimental animals by large doses of estrogen The tumor expands steadily in the affected kidney and may reach a considerable size before any symptoms appear. The classical symptoms are hematuria (the passing of blood in the urine), with or without dull dragging discomfort in the affected loin.
Hematoria has many other causes, but the possibility of malignancy must always be excluded by thorough investigation. The diagnosis can be confirmed by simple radiography and the treatment is by surgical removal of the whole tumor bearing kidney.
As untreated or unsuspected disease progresses, the tumor enters the renal vein and widespread skeletal and pulmonary metastases are the general rule. In these circumstances radiotherapy and chemotherapy are of little value, but some patients obtain temporary remissions from hormonal therapy.
Renal carcinomas demonstrate a few unusual characteristics. In most cancers the recognition of even one distant metastasis indicates that many other metastases are already present. A solitary metastasis can occur in a renal carcioma, however, and in such a circumstances surgical removal of the diseased kidney with it is solitary metastasis is justifiable.
Sometimes such a treatment is carried out inadvertently, it is not uncommon for a symptomless and unsuspected renal tumor to declares itself by the appearance of a solitary metastasis in the lung, a bone, or the brain, and under such a circumstance it may be removed by a thoracic surgeon, an orthopedic surgeon, or a neuro surgeon under the impression that he is dealing with a primary tumor. Microscopic examination establishes the correct diagnosis, and if no other obvious metastases are present the correct treatment in then to remove the diseases kidney.
A few cases of renal cancer are on record in which removal of the primary tumor in the presence of known metastases has resulted in regression and disappearance of the metastases. This, it must be emphasized, is a very rare occurrence, but the fact that it can happen at all is remarkable.