There is no antigen or other specific biological marker for the kidney as in the case of the prostate specific antigen (PSA) for the prostate and there is no means of early detection of this form of cancer.
At present, 40% of kidney tumours are discovered accidentally during some examination involving imagery of the region (notably ultrasounds) carried out for some other reason
The increase in imagery by layer, abdomino pelvic scans and examinations by magnetic resonance (MRI), required for completely different reasons, notably digestive problems , biliary/renal colic reflecting the migration of urinary stones , etc., make the diagnosis of a large number of kidney tumours possible, often small at a less aggressive stage, there almost certainly curable.
Is kidney biopsy mandatory for cancer diagnosis?
Examinations by imagery (ultrasound), along with a scan (tomodensimetry) suffice to confirm kidney cancer. Apart from exceptional cases, it is not necessary to carry out a biopsy by needle or to take other samples to confirm this diagnosis.
Any ‘full mass’, presenting a tissue density to the scanner (the density of that mass increases after injection of the product of contrast) is a kidney cancer in the absence of proof to the contrary.
The proof to the contrary is the surgical removal of the tumour, according to techniques which will be discussed below, followed by anatomo-pathological examination.
Does benign kidney tumors exist?
Certainly, and above all for liquid tumours, not effecting the tissue which are very frequent, these are kidney cysts, isolated or multiple and easy to identify with cancer echography.
But in the case of a cyst with atypical echographic characteristics:
- its content is not completely liquid,
- its walls are thickened
- it presents partitions
- calcifications are present in the partitions or the walls of the
Use of a scanner appears essential as well as great care and caution
Benign parenchymatose tumours or those with reduced malignity represent less than 10% of the tissue tumors of the kidney.
The most frequent, the angiomyolipoma, have quite distinct characteristics in imaging because of their fatty content, notably appearing in magnetic resonance, which usually allows diagnosis before the decision on therapy. In any case, this tumour is also a surgical indication of the risks of haemorrhage which it involves.
The oncocytoma is a tumour with attenuated malignity which is also not exceptional. (5% of malignant kidney tumours). It can have a rosette appearance with central scar of characteristic type under the scanner. In rare cases of doubt, after multi-disciplinary discussion, notably with radiologists, needle biopsies may be necessary.
If the diagnostic of oncocytoma is formally confirmed by imagery, surgery is not necessary and simple monitoring is recommended because the development of this tumour is slow and the prognosis excellent.
Other benign tumours are rare and usually not distinguishable from cancer by imagery. Once the tumour is removed, it is the anatamo-pathological examination which decides. It is better to remove a benign tumour than ignore a cancer.
What is the interest of the scanner?
An abdominal-pelvic scan, with injection, and a thoracic scan to verify the absence of pulmonary metastases are the examinations necessary, and usually sufficient, for the assessment of kidney cancer essential for the choice of treatment.
Some prefer MRI to the scanner. This is in any case essential in case of the kidney cancer spreading to the inferior vena cava because this is the best examination to assess the level to which the clot in the vein axis has risen, and therefore to determine surgical tactics.
In any case, imagery by layer (scan or MRI) provides the urologist with the information he needs concerning:
- the tumour: size, location central to the kidney or peripheral on the extremities, extension to neighbouring organs or the fat layer, invasion of renal cavities;
- the eventual existence of a cancerous growth in the renal vein and in the inferior vena cava;
- the possible presence of large lymphatic nodes along the main vessels, the aorta on the left and the inferior vena cava in case of a tumour on the right;
- the state of the liver and that of the thoracic and lumbar vertebrae;
- the anatomy of the vessels of the cancerous kidney and especially the layout of the renal artery and vein, which are subject to diverse and typical variations. This information is useful to determine surgical tactics;
- the state of the other kidney which needs to provide all of the renal function .
Is there a need for some other examination?
The need for a scintigram of the skeleton to search for bone metastases is rare. It is necessary on a case by case basis, to take account of biological evidence for example.
The assessment of the extension of the tumour is completed by an assessment of the general state of health of the patient: age taken into consideration for guidance on therapy but also medical and surgical history and the state of the main functions, notably circulation and respiration but above all the renal function.
All the parameters thus assessed provide the information to balance expected benefits for the patient from the treatments to be proposed with the risks involved, especially lethal risk.
The history of renal cancer indicates that the speed of development is usually relatively slow: the time for doubling of the size of the tumour is of the order of two years. But metastases, sometimes solitary, can occur even at great distance from a surgical operation, sometimes after more than 15 years without new cancerous development.
A long period of annual monitoring is, therefore, necessary after treatment of a renal cancer.