Kidney cancer

What is kidney cancer?

There are several types of kidney cancer but over 9 out of 10 kidney cancers are "renal cell cancer". This is sometimes called renal adenocarcinoma or renal cell carcinoma or hypernephroma.

Renal cell cancer

This type of cancer develops from a cell in a kidney tubule, which becomes cancerous (malignant). The cancer grows and forms into a tumour within the kidney. As the tumour grows:

• The affected kidney tends to become larger. In time the tumour may grow through the wall of the kidney and invade nearby tissues and organs, such as the muscles around the spine, the liver, the nearby large blood vessels, etc.

• Some cells may break off into the lymph channels or bloodstream. The cancer may then spread to nearby lymph nodes or to other areas of the body (metastasise).

Renal cell cancers can be divided into several subtypes by looking at certain features of the cells under a microscope. Most are clear cell renal cell cancers. However, some other types occur such as sarcomatoid, or granular renal cell cancers. Knowing the subtype of the cancer can be important, as some respond to treatment better than others.

Other types of kidney cancer

Some rare types of cancer arise from other types of cell within the kidney. For example:

• Transitional cell (urothelial) cancers are cancers which arise from transitional cells. These are cells which line the renal pelvis, ureters and bladder. Transitional cell cancer is common in the bladder but in some cases it develops in the renal pelvis.

• Wilms' tumour and clear cell sarcoma of the kidney are types of kidney cancer which develop only in children.

See the separate leaflet called Cancer for more general information about cancer

The rest of this leaflet only discusses renal cell cancer.

What causes kidney cancer (renal cell cancer)?

In the UK, over 12,500 people are diagnosed with kidney cancer each year. Some people develop kidney cancer for no apparent reason. However, certain risk factors increase the chance that kidney cancer may develop. These include:

• Age. Most cases develop in people over the age of 60. It is uncommon in people aged under 50. It is also more common in men.

• Smoking. About a third of kidney cancers are thought to be caused by smoking. Some of the chemicals from tobacco get into the body and are passed out in urine. These chemicals in the urine can be damaging (carcinogenic) to kidney tubule cells. Pipe and cigar smoking are as harmful as cigarette smoking.

• Other chemical carcinogens. Some workplace chemicals have been linked to an increased risk of kidney cancer - for example, asbestos, cadmium and some organic solvents.

• Obesity. Obesity is an established risk factor for kidney cancer. About a quarter of kidney cancer cases are due to being overweight.

• Chronic kidney disease.

• High blood pressure (hypertension). There is a greater risk in people who have high blood pressure.

• Genetic factors may play a role in some cases. (A faulty gene which runs in some families may sometimes trigger kidney cancer. Also, people with some rare genetic disorders have a higher risk of developing kidney cancer - for example, von Hippel-Lindau syndrome, Birt-Hogg-Dubé syndrome and tuberous sclerosis.)

See the separate leaflet called Causes of cancer for more general details about cancer.

What can I do to protect myself against kidney cancer?

The following lifestyles have been shown to reduce the risk of kidney cancer:

• Eating fatty fish regularly for several years.

• Eating plenty of fruit and vegetables.

• Drinking 1 or 2 units of alcohol a day.

It is thought that half of all kidney cancers would be avoided if smoking and obesity were eliminated.

What are the symptoms of kidney cancer?

Many people with kidney cancer have no symptoms at first, especially when the cancer is small. As the cancer develops, the following may occur.

Blood in urine

In many cases, the first symptom is to pass blood in the urine (haematuria), which is usually painless. The blood in the urine may come and go as the tumour bleeds from time to time. (There are many causes of blood in the urine apart from kidney cancer, such as bladder or kidney infections, bladder cancer, inflammation of the kidney, kidney stones, etc. Medical advice should always be sought for blood in the urine.)

Other symptoms of kidney cancer

Various other kidney cancer symptoms may occur, typically as the tumour becomes larger. They include:

• Pain or discomfort in the side or back of the abdomen (loin pain).

• High temperatures (fevers) and sweats.

• A swelling in the area over a kidney.

• Anaemia, which can cause tiredness and paleness.

• Some renal cell tumours produce abnormal amounts of certain hormones. This can lead to problems such as:

  • A high blood calcium level which can cause various symptoms, such as increased thirst, feeling sick, tiredness, and constipation.

  • Too many red blood cells being made (polycythaemia).

  • High blood pressure (hypertension).

As the cancer becomes larger, weight loss and a general feeling of "being unwell" might occur. If the cancer spreads to other parts of the body, various other symptoms can develop.

How is kidney cancer diagnosed and assessed?

A doctor may suspect that kidney cancer from the symptoms and signs listed above and then arrange tests to confirm the diagnosis. However, in developed countries, about half of kidney cancers are diagnosed before any symptoms develop. They are usually seen by chance when a scan or other investigation is done for another reason.

Confirming the diagnosis

Where there is a suspicion of kidney cancer, the National Institute for Health and Clinical Care (NICE) has advised that cancer should be diagnosed or ruled out within 28 days of a referral to a specialist. Scans such as an ultrasound scan or a computerised tomography (CT) scan will usually be organised by the specialist after referral.

Assessing the extent and spread

After a diagnosis of kidney cancer, other tests are likely to be advised. These may include one or more of: a magnetic resonance imaging (MRI) scan of the abdomen and chest, a chest X-ray, kidney function blood tests and sometimes other tests. This assessment is called staging of the cancer.

The aim of staging is to find out:

• How much the tumour in the kidney has grown and whether it has grown to the edge, or through the outer part of the kidney.

• Whether the cancer has spread to local lymph glands (nodes).

• Whether the cancer has spread to other areas of the body (metastasised).

Finding out the stage of the cancer helps doctors to advise on the best treatment options. It also gives a reasonable indication of outlook (prognosis). See the separate leaflet called Stages of cancer for more details.

Treatments for kidney cancer

Treatment options which may be considered include surgery, radiotherapy, arterial embolisation, immunotherapy and systemic targeted molecular therapies. (In general, chemotherapy does not work as well for renal cell cancer as for some other types of cancer. Therefore, it is less often used as a treatment.) The treatment advised for each case depends on various factors, such as:

• The stage of the cancer (how large the cancer is and whether it has spread).

• The exact subtype or grade of the cancer.

• The general health of the person.

The specialist will be able to give the pros and cons, likely success rate, possible side-effects and other details about the various possible treatment options for any particular cancer.

The aims of treatment should also be discussed. For example:

• In some cases, the treatment aims to cure the cancer. Some kidney cancers can be cured, particularly if they are treated in the early stages of the disease. (Doctors tend to use the word remission rather than the word cured. Remission means there is no evidence of cancer following treatment. If you are in remission, you may be cured. However, in some cases a cancer returns months or years later.)

• In some cases, the treatment aims to control the cancer. If a cure is not realistic, with treatment it is often possible to limit the growth or spread of the cancer so that it progresses less rapidly. This may keep you free of symptoms for some time. With the development of immunotherapy and systemic targeted therapies this is often successful for many years.

• In some cases, treatment aims to ease symptoms. For example, if a cancer is advanced then treatments such as painkillers or other treatments may be used to help manage pain or other symptoms.

Surgery

An operation to remove some (or sometimes all) of the affected kidney is the most common treatment. Nowadays this is often laparoscopic (keyhole) surgery. Laparoscopic surgery helps to reduce complications of surgery and leads to a shorter stay in hospital. It appears to have the same outcomes in terms of treating the cancer as open surgery.

If the cancer is at an early stage and has not spread then surgery alone may be curative. If the cancer has spread to other parts of the body, surgery to remove the affected kidney may still be advised, often in addition to other treatments.

In some cases, surgery is done to remove a secondary kidney tumour which has spread to another part of the body. For example, some secondary tumours which develop in the liver or lung can be removed.

Radiotherapy

Radiotherapy is a treatment which uses high-energy beams of radiation which are focused on cancerous (malignant) tissue. This kills cancer cells, or stops cancer cells from multiplying. See the separate leaflet called Radiotherapy for more details.

Radiotherapy was previously rarely used for renal cell carcinoma but newer methods have enabled the delivery of radiation treatment directly to the area (the kidney itself or somewhere else in the body where the kidney cancer has spread) which appears to be both safe and effective.

Immunotherapy (sometimes called biological therapy) and targeted molecular therapies

Immunotherapy using interferon and aldesleukin (sometimes called interleukin 2) was commonly used to treat kidney cancer. This treatment uses medicines to stimulate the immune system to attack cancerous cells.

However, more recently, new targeted treatments have been introduced including sunitinib, sorafenib, pazopanib and temsirolimus. They are types of medicines called multikinase inhibitors which interfere with the growth of cancer cells. They also work by slowing the growth of new blood vessels within the tumour. They can shrink the cancer or slow its growth.

In 2022, NICE recommended that a medication called pembrolizumab can be used with routine surveillance after surgery (nephrectomy or partial nephrectomy) for kidney cancer, to keep the cancer at bay. This combination has been shown to increase the time people have before their cancer comes back and also life expectancy.

Other treatments

Using local anaesthetic with sedation or a general anaesthetic, radiofrequency (using electrodes inserted through the skin) or cryotherapy (using probes inserted through the skin or in a laparoscope) may be used as an option in the treatment of kidney cancer. Radiofrequency is delivered via an electrode to destroy the tumour tissue in the target area. Radiofrequency and cryotherapy appear to have similar outcomes for treating the kidney cancer.

Cryotherapy

This treatment involves using a coolant at subfreezing temperatures to create an ice ball around the probe's tip, which then destroys surrounding tissue. Irreversible electroporation uses electricity to damage cancer cells. These treatments may only be available at specialist centres where the doctors are trained to do them. Recent evidence suggests that cryotherapy should be further investigated but is unlikely to be as successful as surgery. It may be useful for patients who are too frail or unwell to have surgery. In the UK, NICE has advised this is only to be used in specialist centres.

What is the outlook for kidney cancer?

The outlook (prognosis) is best in those whose cancer is diagnosed when it is still confined within a kidney and has not spread, and who are otherwise in general good health. Surgical removal of an affected kidney in this situation gives a good chance of cure.

However, many people with kidney cancer are diagnosed when the cancer has already spread. In this situation a cure is less likely but treatment can often slow down the progression of the cancer. With newer treatments the cancer may be kept at bay for many years.

The response to treatment can vary from case to case. This may be partly related to the exact subtype or grade of the cancer. Some kidney cancers, even some which are advanced and have spread, respond much better to treatment than others.

What are the kidneys?

Cross-section diagram of the urinary tract

The two kidneys lie to the sides of the upper part of the abdomen, behind the intestines, and either side of the spine. Each kidney is about the size of an orange, but bean-shaped.

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A large renal artery takes blood to each kidney. The artery divides into many tiny blood vessels (capillaries) throughout the kidney. Tiny structures in the kidneys, called nephrons, filter the blood contained in the capillaries. Water and waste materials which filter through the walls of the capillaries into the nephrons form urine.

Urine passes along thin channels (tubules) which are part of each nephron, into larger channels (ducts) which drain the urine into the inner part of the kidney (the renal pelvis).

Urine passes down a tube called a ureter which goes from each kidney to the bladder.

Urine is stored in the bladder until it is passed out through the tube called the urethra when we go to the toilet.

The cleaned (filtered) blood from each kidney collects into a large renal vein which takes the blood back towards the heart.

Some specialised cells in the kidneys also make some hormones, including:

• Renin - which helps to regulate blood pressure.

• Erythropoietin - which helps to stimulate the bone marrow to make red blood cells.

• Calcitriol - which helps to regulate the calcium level in the blood.

Although it is normal to have two kidneys, we can live perfectly well with just one healthy kidney.