Kidney cancer is a type of cancer that may develop in the kidneys. Your kidneys are two bean-shaped organs found behind your abdominal organs on either side of your spine.
Causes of kidney cancer
Most kidney cancers (85%) are renal cell carcinoma (RCC). A less common type of kidney cancer is called transitional cell carcinoma (TCC). There are other rare types of kidney cancer including sarcomas and a secondary spread from another primary cancer elsewhere in the body (metastasis).
RCC usually presents as a solid mass in the meaty part of the kidney, whereas TCC looks like a frondy, irregular mass in the inner part of the kidney that contains urine. They are of different cells of origin and are managed differently.
How common is kidney cancer?
In Victoria, Australia, more than 630 people are diagnosed with kidney cancer each year. It accounts for 3% of all adult cancers. Most patients present in the fifth to seventh decades of life. Men are affected twice as often as women.
What are the causes of RCC?
The exact causes are unknown, but the strongest risk factor is smoking (twofold risk). Those with a family history of kidney cancer are at risk; they may inherit a gene that predisposes them to kidney cancer. Von Hipple-Lindau disease and tuberous sclerosis are two such genetic conditions. There is also an increased incidence of RCC in patients with horseshoe kidneys, adult polycystic kidney disease and in dialysis patients who develop kidney cysts.
What are the signs and symptoms?
An increasing number of cases are found as incidental kidney masses with no symptoms, on imaging studies obtained for another purpose.
Otherwise, the signs and symptoms include:
- Blood in the urine (haematuria) – which may or may not be visible.
- Flank pain.
- Palpable abdominal mass.
- Weight loss.
- Constant fatigue.
- Night sweats.
- Sudden swelling of the veins in the testicle (varicocele).
Less common signs and symptoms include:
- Raised calcium levels in the blood.
- Abnormal liver function studies of the blood.
- High red cell count in the blood.
- High blood pressure.
- Bony pain (spread of cancer to bones).
- Shortness of breath or cough (spread to the lungs).
What does the evaluation of kidney cancer involve?
Investigations are done to diagnose the cancer and also to assess how advanced it is. Not all the tests are necessary for every patient.
An ultrasound scan performed for other reasons may be the first study that detected the incidental kidney mass. The ultrasound can tell how big the cancer is, whether there are any fluid components (cystic mass), and if the cancer has spread to the kidney vein. It is painless, quick and does not involve radiation. However, it is not as accurate as a CT scan in terms of visualising the anatomy of the kidney and other abdominal organs.
A CT scan is essential when evaluating kidney cancer. A 3D reconstruction of the kidney anatomy and surrounding organs can be useful when planning surgery. It can look for spread of cancer to other organs. If intravenous contrast is given, it can differentiate between a benign and a cancerous mass. It can also look for kidney obstruction and enhance the inner part of the kidney, which contains urine, to look for TCC.
MRI scans are not routinely done unless there is suspicion that the cancer has spread to the kidney vein or the spinal cord.
Kidney nuclear scan
A kidney nuclear scan gives information on how much each kidney contributes to the overall function. A normal person needs only one kidney to survive; if one kidney is removed, the other one will take over. However, there are some patients who have a kidney that contributes significantly more to the overall kidney function than the other one. Removing this ‘dominant’ kidney carries the risk of the patient becoming dialysis-dependant. In such cases, other treatment options like kidney-sparing surgery may be considered (see below).
A simple test to look for the spread of cancer to the lungs.
This test is done to look for the spread of cancer to the bones, which will turn up as a dark spot on the scan.
A urine test can look for the presence of blood in the urine. It can also look for cancer cells which are found in TCC of the urinary tract.
A blood test can assess one’s red blood cell count to look for anaemia. Other things to look for are raised calcium levels and abnormal liver function tests.
When a patient has blood in the urine, a cystoscopy (inspection of the bladder with a tube-like camera) is one of the important tests to do. This can rule out a lower urinary tract (bladder, prostate, urethra) cause of bleeding which may not be easily picked up by imaging studies.
A kidney biopsy is a sampling of the kidney tissue obtained by a needle inserted from the back into the kidney under imaging guidance. In some cases, this may help in the diagnosis of kidney cancer. There may be a significant rate of sampling errors (false-negatives) and that is why a biopsy is not a routine test.
It may be indicated if:
- The kidney mass is small and there is doubt about whether it is a cancer.
- Lymphoma of the kidney is suspected.
- There is a history of another primary cancer. A biopsy is done to rule out the spread of that cancer to the kidney.
What are the treatment options for localised RCC?
The treatment options for localised kidney cancer are observation, surgery and targeted therapy.
Not all kidney cancers need to be surgically removed. The risk of a small cancer (<3cm) spreading to other organs is small (1% – 2%). Therefore, it is reasonable to observe such small cancers in some patients, especially those who are frail or elderly.
Surgery is the main treatment for kidney cancer. Even if the cancer is advanced and has spread to other organs, surgery has the benefit of controlling bleeding from the kidney and improving the overall survival of the patient. However, surgery is not always possible for every patient.
This is the surgical removal of the whole kidney with the cancer, together with surrounding fat or lymph nodes if possible and the adrenal gland if needed. It may be done through keyhole surgery (laparoscopic or robotic) or an open incision.
Partial nephrectomy (kidney-sparing surgery)
Partial nephrectomy involves surgical removal of only the part of the kidney that has cancer. This ensures the preservation of as much kidney function as possible. This is indicated if the patient is at risk of complete kidney failure and becoming dialysis-dependant, after removing the affected kidney. Examples of such patients are those with cancers in both kidneys, or cancer in the one remaining good kidney. It is also done for some patients with small kidney cancers (<4cm).
The kidney mass can be targeted with radio wave heat treatment (radiofrequency ablation) or with freezing treatment (cryotherapy). This is done with a probing needle that is inserted into the kidney cancer to deliver the treatment. It is only suitable for small kidney cancers (<4cm).
What if the cancer has spread to other organs?
Up to one-third of patients with RCC will have spread of the cancer to other organs at the time of diagnosis. Some of the treatments involve being part of a clinical trial.
The kidney cancer itself is not sensitive to radiotherapy, but it can be given to other organs (e.g., bone) that are involved, to relieve pain.
Immunotherapy is the administration of some naturally produced substances in the body to stimulate the immune system to fight the cancer.
Tyrosine kinase inhibitors
These drugs act by decreasing the growth of blood vessels supplying the cancer and thus, result in tumour shrinkage. The administration of these drugs is supervised by a medical oncologist (cancer specialist). They have shown promising results and can improve overall survival by a few months.
These drugs are given either orally or intravenously. They are often used in late stage RCC.
Other therapy for advanced RCC
These drugs include monoclonal antibodies and kinase inhibitors. They act by stopping the growth of blood vessels in the cancer, causing it to starve and shrink.
How is the treatment for TCC different from RCC of the kidney?
TCC of the kidney is somewhat like TCC of the bladder (see bladder cancer), because they arise from the same cells found in the inner lining of the urinary tract (transitional cell). This same cell lining covers the inner part of the kidneys, ureters and the bladder. Therefore, the ureter is removed at the same time when surgically removing a kidney with TCC, due to the likelihood of the TCC recurring in the ureter and the difficulty of monitoring for that. There is no such risk in the case of RCC and hence the ureter is not removed during surgical removal of a kidney with RCC.
Read A/Prof Gani’s publication on the role of CT vs. MRI for kidney cancer staging:
Download Multidetector computed tomography vs magnetic resonance imaging for defining the upper limit of tumour thrombus in renal cell carcinoma - PDF (159 Kb)