About Kidney Cancer

Author : Bhadresh Bundela

Kidney cancer

The usual type of kidney (renal) cancer is a carcinoma.The commonest type is the clear cell type and this is the one associated with VHL gene mutations. However, a significant minority of cancers are of the papillary type and another subset arise, not from the parenchymal kidney, but from the pelvis - these usually being of transitional cell histology and more resembling a bladder cancer; indeed there may well be a multiplicity of such transitional cell cancers in the urothelium.

Incidence of kidney cancer

Cancer of the kidney accounts for 2% of all cancer deaths and the age range most at risk is 60-70 years. There is slight male dominance in incidence (male:female = 1.5:1). Approximately 2% of cases are associated with inherited syndromes.

Causes of kidney cancer

There are geographic differences in the incidence such that the disease is rare in Japan compared with the Western world. There is a familial incidence of this disease in 2% of cases and the most importantly recognised is the association with von Hippel Lindau syndrome.Von Hippel Lindau syndrome is a disease inherited as an autosomal dominant but actually caused by the inheritance of a tumour suppressor gene (VHL); the syndrome comprises clinically: retinal angiomas, haemangioblastomas of the central nervous system, phaeochromocytomas and renal cell carcinoma of the clear cell type. What has caught the focus of the oncology community in recent years is the fact that the VHL gene seems to be responsible not only for the development of renal cell carcinoma in the VHL syndrome, but also that in 60% or more of the sporadic population of sufferers of clear cell renal cancer.

VHL protein (the product of the gene) functions as a tumour suppressor, inhibiting growth when introduced into cultures of renal cell carcinoma cells in vitro. Hypoxia inducible factor (HIF) and genes are normally inhibited by by VHL protein, including several involved in angiogenesis (e.g. vascular endothelial growth factor: VEGF), cell growth (e.g. transforming growth factor alpha: TGFa)etc. When VHL protein is lost these proteins are over-expressed leading to a micro-environment favourable for cancer growth. This is thought currently to be the major oncogenic pathway leading to renal cancer. Distinct from the von Hippel Lindau syndrome, familial clear cell renal cancer has been reported in patients with translocations of chromosome 3p at a fragile 3p14 locus, but there may well be a common pathway through the VHL protein to oncogenesis.

Screening for kidney cancer

No screening tests are indicated as the disease is sufficiently unusual for the pick up rate on routine abdominal scanning being so low as to not be feasible on health economics. There is one exception and that is the Von Hippel Lindau group of patients, who are sufficiently at high enough risk to warrant such screening by abdominal scanning.

Symptoms of kidney cancer

Pain in the loin is a common feature that brings the patient to the doctor and blood in the urine is a second relatively common complaint. Sometimes the patient can feel the development of a lump in the loin. Lastly, the cancer may have spread and present because of symptoms referable to the metastases (e.g. bone pain).

Diagnosis of kidney cancer

An abdominal scan is the first test that indicates that there is a mass arising from the kidney, and an ultrasound scan tells whether it is truly solid and therefore likely to be a tumour.

Stages of kidney cancer

The cancer spreads locally into the flank and then metastasises further afield, especially to the bones, lungs and also the brain and liver. 25% of patients present with metastatic disease. Symptoms of these metastatic sites of spread depend on the exact localisation of the spread – e.g. bone pain in the spine, pressure symptoms from brain metastases, coughing up blood from lung metastatic spread etc.

The staging therefore includes chest x-ray or CT scanning of the lungs as well as scanning of the abdomen. A whole body bone scan is also a part of the routine work-up.After CT scanning of the body and bone scan, the clnican should know whether the cancer has spread from the kidney.