Brief overview
- What is kidney cancer (renal carcinoma)? A malignant tumor of the kidney, with renal cell cancer (renal cell carcinoma) being the most common variant. Most patients are older men.
- Symptoms: Usually none at first, later usually blood in the urine and kidney/flank pain. The tumor may be palpable. Other possible symptoms: Fatigue, fever, lack of appetite, weight loss, anemia, high blood pressure and possibly signs of metastases such as bone pain, shortness of breath, headaches, etc.
- Causes: Not exactly known. Risk factors are smoking, obesity, high blood pressure, end-stage renal failure, genetic predisposition and advanced age.
- Diagnostics: Doctor-patient consultation, physical examination, laboratory tests, imaging (ultrasound, computer tomography, magnetic resonance imaging), biopsy if necessary. Further examinations for tumor spread.
- Therapy: Surgical removal if possible. If the tumor is small, active monitoring or ablative therapy (e.g. destruction with cold). In advanced stages, as an alternative or in addition to surgery, drug therapy, radiotherapy.
- Prognosis: Relatively good if the kidney cancer is detected and treated in good time. However, if there are already metastases of kidney cancer, the life expectancy (chance of survival) of those affected is significantly lower.
What is kidney cancer?
By far the most common variant in adults is renal cell cancer (renal cell carcinoma, adenocarcinoma of the kidney). It develops from epithelial cells of the nephrons (nephron = basic functional unit of the kidneys). There are different types of renal cell carcinoma: By far the most common is the so-called clear cell carcinoma; less common are, for example, papillary carcinoma and ductus Bellini carcinoma.
This article refers primarily to renal cell carcinoma!
In addition to renal cell carcinoma, other malignant kidney tumors also fall under the term kidney cancer. These include, for example, the rarer renal pelvis carcinoma. It develops from the tissue of the urinary tract, which originates from the kidneys.
In children, the most common form of malignant kidney tumor is not renal cell carcinoma but the so-called nephroblastoma (Wilms tumor). It develops from cells that resemble kidney cells in the embryo, which is why it is referred to as an embryonal tumor. Overall, however, children rarely develop a malignant kidney tumor.
Kidney metastases and kidney cancer metastases
In some cases, a malignant growth in the kidney does not turn out to be kidney cancer, but a metastasis of another type of cancer somewhere in the body. Such kidney metastases can be caused by lung cancer or breast cancer, for example.
As soon as the first metastases have formed, the prognosis and chances of recovery deteriorate for patients with kidney cancer.
Function of the kidneys
The paired kidneys perform vital tasks in the body: first and foremost, they continuously filter the blood, removing harmful substances, among other things, which are then excreted in the urine they produce.
The kidneys also help to regulate the water and electrolyte balance as well as the acid-base balance. Last but not least, they produce two hormones: renin (important for regulating blood pressure) and erythropoietin (involved in the regulation of erythrocyte production).
You can find out more about these tasks of the kidneys in the article Kidney function.
Kidney cancer: frequency
Kidney cancer – by far the most common type of renal cell cancer – mainly affects older men. Overall, it is a rather rare form of cancer:
In Germany, the Center for Cancer Registry Data (Robert Koch Institute) registered a total of 14,029 new cases in 2017, in 8,864 men and 5,165 women. This means that kidney cancer accounted for just under 2.9 percent of all new cancer cases* (489,178) that year.
How can you recognize kidney cancer?
Kidney cancer (renal cell carcinoma) often does not cause any symptoms for a long time. The first symptoms usually only appear in more advanced stages – when the tumor has reached a certain size and/or has metastasized to more distant regions: Kidney cancer then often causes blood in the urine (hematuria) and pain in the kidney area or flank pain. In some patients, the tumor can be felt.
General symptoms of kidney cancer can include tiredness, fever, loss of appetite and unwanted weight loss. However, these symptoms are very unspecific – they can also occur with other forms of cancer and many other diseases.
Other possible kidney cancer symptoms include high blood pressure (hypertension), anemia and an elevated calcium level in the blood (hypercalcemia). Liver dysfunction with an increase in alkaline phosphatase (AP) in the blood – known as Stauffer’s syndrome – is typical of renal cell carcinoma.
In male patients, there may be a further sign of kidney cancer: If the tumor breaks into one of the renal veins, a varicose vein in the testicle (varicocele) may develop.
Metastatic kidney cancer: symptoms
Kidney cancer: causes and risk factors
The causes of kidney cancer or renal cell cancer are still largely unknown. However, there are a number of proven risk factors that favor the onset of the disease. These include
- smoking
- obesity
- High blood pressure
- Terminal renal insufficiency: This refers to chronic kidney failure in stage 5 (end stage). Possible causes include kidney damage due to diabetes or high blood pressure as well as polycystic kidney disease (genetic disease in which numerous fluid-filled cavities form in the kidneys).
- Genetic predisposition: In rare cases, hereditary genetic mutations contribute to the development of renal cell cancer (hereditary renal cell carcinoma). The most common of these is von Hippel-Lindau syndrome, caused by mutations in the VHL gene. They significantly increase the risk of clear cell carcinoma (the most common form of renal cell cancer).
Older age is also associated with an increased risk of kidney cancer. Life expectancy and prognosis are then usually influenced by concomitant diseases, which very often occur in old age (e.g. cardiovascular diseases).
Influence of diet unclear
The links between nutritional factors and the risk of renal cell cancer are contradictory. There is also no evidence that fruit and vegetable consumption could prevent the development of tumors. Overall, the data currently available do not allow any conclusions to be drawn about the possible influence of certain foods or nutrients on the development of renal cell cancer.
How is kidney cancer diagnosed?
Kidney cancer (renal cell cancer) is increasingly being discovered by chance: As part of examinations carried out for other reasons (e.g. ultrasound examination or computer tomography of the abdomen), many patients come across the malignant kidney tumor. It is often still quite small, i.e. not very advanced.
In other cases, the diagnosis of kidney cancer is only made when symptoms of the already advanced tumor prompt the patient to see a doctor.
Medical history and physical examination
In the case of unexplained symptoms, the medical history is routinely taken first (anamnesis): The doctor asks exactly what complaints the patient has, how pronounced they are and how long they have existed. He will also ask about any previous or underlying illnesses.
However, further examinations are required to diagnose kidney cancer. There are also examinations that can be used to determine the extent of the cancer (e.g. presence of metastases). This is important for treatment planning.
Laboratory tests
Laboratory tests can detect pathological changes in the patient’s blood and urine samples. If kidney cancer is suspected, blood values such as blood count, blood coagulation and electrolytes in the blood (such as sodium, potassium, calcium) are determined. In addition, the blood level of alkaline phosphatase (AP), the kidney values in the blood and urine and the liver values are measured.
The urine is also examined for the presence of blood (hematuria). Sometimes this blood content is so large that the urine is visibly reddish in color (macrohematuria). In other cases, invisible amounts of blood are found in the urine (microhaematuria).
Imaging procedures
If the kidney tumor is of a certain size, it can usually be detected using an ultrasound examination (sonography). Computed tomography (CT) offers a much higher image resolution. It is the standard procedure for detecting small kidney tumors. It is also used to determine the extent of the cancer (staging) and to plan the surgical removal of the tumor.
Biopsy
Imaging is usually sufficient to diagnose kidney cancer (renal cell cancer) with certainty. However, if the diagnosis is still unclear afterwards, it is possible to take a tissue sample and examine it under a microscope (biopsy). However, this should only be done if the choice of treatment depends on the results of the examination. If, on the other hand, it is clear from the outset that an unclear kidney tumor will be surgically removed, for example, a tissue sample should not be taken beforehand.
The reason for this is that taking a sample is associated with certain risks (including bleeding). A kidney biopsy is therefore only recommended in certain cases – such as when deciding on treatment for an unclear kidney tumor. In addition, a biopsy should or can be carried out in the following cases to confirm the diagnosis:
- before ablative therapy – i.e. before targeted destruction of the tumor tissue using cold (cryoablation) or heat (radiofrequency ablation)
- in patients with metastases before a planned kidney removal (cytoreductive nephrectomy)
In contrast, a biopsy is not recommended for cystic kidney tumors (= kidney tumors with fluid-filled cavities). One reason for this is the potential risk of cyst fluid leaking into healthy tissue during sampling and thus spreading tumor cells.
The biopsy should be performed as a punch needle biopsy. Under ultrasound or CT guidance, a fine hollow needle is “shot” into the tumor tissue via the abdominal wall using a punching device in order to obtain a cylindrical tissue sample. At least two such tissue cylinders should be taken. The patient is given a local anesthetic before the biopsy.
Further examinations
Once the diagnosis of kidney cancer (renal cell cancer) has been confirmed, it is important to find out how far the cancer has already spread in the body (spread diagnostics). Which examinations are necessary and useful for this depends on the individual case.
For example, all symptom-free patients whose kidney tumor is larger than three centimetres should have a computer tomography of the chest (thoracic CT). The larger the tumor, the greater the likelihood of metastases, for example in the lungs.
If brain metastases are suspected (e.g. due to seizures, paralysis, headaches), magnetic resonance imaging of the skull (cranial MRI) is recommended. For better imaging, the patient should be injected with a contrast agent before the examination.
If there are possible signs of bone metastases (e.g. pain), the patient’s entire body is examined using CT or MRI (whole-body CT or MRI).
Kidney cancer: Therapy
The stage of the tumor has the greatest influence on the type of treatment for kidney cancer. However, the patient’s age and general state of health are also taken into account when planning treatment.
In principle, localized (non-metastatic) renal cell cancer is operated on if possible: If it is possible to completely excise the malignant tumor, the kidney cancer is curable. In certain cases of small kidney tumors, active surveillance or ablative therapy can be chosen as an alternative to surgery.
In the case of renal cell carcinoma with metastases, a cure is usually no longer possible – i.e. no curative therapy aimed at a cure. Instead, people with terminal kidney cancer receive palliative therapy. This aims to prevent or alleviate symptoms, improve the patient’s quality of life and prolong their life. Various treatment options are available for this purpose.
For example, the tumor on the kidney and the individual metastases can be treated locally using surgery and/or radiotherapy. In addition, drugs are available to treat kidney cancer that affect the whole body (systemic therapy).
Active surveillance
In the case of a small renal cell carcinoma that has not yet metastasized, treatment may be limited to active surveillance. This consists of regular check-ups in which the tumor growth is checked using imaging techniques.
Such active surveillance can be useful for patients for whom surgical removal of the tumor or other forms of cancer therapy would be too stressful – for example, patients with other illnesses and/or a limited life expectancy. Active surveillance is also a possible strategy for patients who refuse surgical or ablative therapy (see below) for their small kidney tumor.
If an actively monitored tumor grows, experts recommend surgical removal.
Ablative therapy
A possible alternative to active surveillance for patients with a small renal cell carcinoma as well as additional diseases and/or limited life expectancy is ablative therapy. This involves the direct destruction of the tumor tissue without major surgery. This is usually done using cold (cryoablation) or heat (radiofrequency ablation):
- Radiofrequency ablation (RFA): Here too, a probe is inserted into the kidney tumor via the abdominal wall or during a laparoscopy. It uses alternating current to heat the cancerous tissue to 60 to 100 degrees Celsius, which destroys it.
In both cases, the insertion and the “work” of the probe are monitored on a screen using imaging techniques (such as ultrasound or CT).
Surgery: different techniques
There are various options and techniques for the surgical treatment of renal cell cancer.
Non-metastatic kidney cancer: surgery
Surgical removal is the treatment of choice for non-metastatic renal cell cancer. Wherever possible, this involves organ-preserving surgery (partial nephrectomy): The surgeon only cuts out the part of the kidney affected by the cancer. In doing so, he takes care to preserve as much healthy kidney tissue as possible.
The procedure is usually performed as open surgery, i.e. via a longer incision (depending on the location of the tumor, for example on the abdomen or flank).
Non-metastatic renal cell carcinoma cannot always be removed in such a way that the rest of the kidney remains intact. In this case, the entire organ must be removed, which doctors call a radical nephrectomy. Normally, however, this is not a problem – the second, healthy kidney can take over all kidney functions on its own.
If patients with non-metastatic renal cell cancer have enlarged lymph nodes, these can be surgically removed in order to examine them for cancer cells. If imaging examinations before or during the operation reveal that an adrenal gland is also affected by the cancer, this is also removed.
Metastatic kidney cancer: surgery
If renal cell cancer has already spread to other organs, it can no longer be cured by surgical removal. Nevertheless, in some cases it may make sense to cut out the malignant kidney tumor. This can alleviate symptoms such as local pain and bleeding. The operation may even prolong a patient’s survival.
Systemic therapy
In the case of advanced and/or metastatic renal cell cancer, cancer drugs are usually administered that act throughout the entire body (i.e. systemically). The following substance groups are available:
- mTOR inhibitors (temsirolimus, everolimus): The enzyme mTOR is generally important for cell growth and supply. Cancer cells contain a particularly large amount of this enzyme and can therefore grow and multiply uncontrollably. mTOR inhibitors restrict this proliferation of cancer cells.
- Checkpoint inhibitors: Immune checkpoints are control points of the immune system that limit immune reactions (e.g. against the body’s own cells) as required. Some cancer tumors (such as kidney cancer) can activate these “brakes” and thus protect themselves from attack by the body’s immune system. Checkpoint inhibitors (such as pembrolizumab, nivolumab) remove these “brakes”.
- VEGF antibodies: The artificially produced antibody bevacizumab inhibits certain binding sites for growth factors (VEGF receptors) and thus the formation of new blood vessels, which the growing kidney tumor needs for its supply.
Doctors decide on a case-by-case basis which medication is most suitable for a kidney cancer patient. Active substances are often combined, for example pembrolizumab plus axitinib. The VEGF antibody bevacizumab is also not given alone in renal cell cancer. Instead, it is always combined with interferon – an active substance that counteracts the growth of cancer cells.
The “classic” drug treatment for most forms of cancer is chemotherapy. However, it is not a treatment option for kidney cancer – i.e. metastatic renal cell cancer – because it is generally ineffective.
Local treatment of kidney cancer metastases
Kidney cancer metastases (lung, bone, etc.) are also often treated locally. The aim is either to increase the chances of recovery or – if the disease is too advanced – to alleviate or prevent symptoms (such as pain).
Depending on the location, size and number of metastases, surgical removal and/or radiation (radiotherapy) can be used. Under certain circumstances (e.g. in the case of some brain metastases), the latter can also take the form of stereotactic radiotherapy. In this case, the malignant tumor is irradiated very precisely from different angles with high intensity.
Supportive therapy
Depending on requirements, kidney cancer symptoms and other consequences of the cancer or cancer therapy are treated in a targeted manner. Examples
This pain therapy can sometimes be usefully supplemented with other medications (co-medications such as muscle relaxants).
In the case of anemia as a result of cancer or cancer therapy, those affected may need blood transfusions.
Cancer patients in general often suffer from pronounced exhaustion (fatigue). Experts recommend individually adapted endurance training as part of exercise therapy.
Kidney cancer patients with bone metastases should receive medication to prevent bone fractures – bisphophonates or the monoclonal antibody denusomab in combination with calcium and vitamin D.
Kidney cancer: course of the disease and prognosis
Most patients are interested in one question above all: can kidney cancer be cured? In fact, the prognosis for the most common form – renal cell cancer – is relatively favorable compared to many other forms of cancer.
In individual cases, however, the chances of recovery depend on how large the tumor on the kidney is and how far it has already spread at the time of diagnosis. The following applies: the earlier the diagnosis and treatment, the better the prognosis for kidney cancer.
The patient’s age and any concomitant diseases also have an influence on the chances of recovery from kidney cancer (renal cell cancer).
Kidney cancer: aftercare and rehabilitation
Even after kidney cancer treatment is completed, patients are not left alone. Aftercare and rehabilitation are the next steps.
Aftercare
Attending the recommended follow-up examinations after kidney cancer is very important. The follow-up appointments serve, among other things, to detect a possible relapse (recurrence) of the kidney cancer and (new) metastases at an early stage. It is also important to keep an eye on the patient’s kidney function.
Follow-up examinations routinely include a doctor-patient consultation (medical history), physical and laboratory examinations and an imaging examination of the abdomen and, if necessary, the chest (ultrasound and/or computer tomography or magnetic resonance imaging).
How often and for how long a kidney cancer patient is invited to follow-up examinations depends largely on their risk of recurrence (low, medium, high). In principle, several follow-up appointments over a period of several years are recommended. Initially, they are scheduled at shorter intervals (e.g. every three months), later at longer intervals (annually).
Rehabilitation after kidney cancer
The details of the rehabilitation program depend on the patient’s needs. However, components from various disciplines are incorporated, for example from medicine, psychology, physiotherapy, occupational therapy and sports therapy.
For example, doctors in rehab take care of existing side effects of cancer therapy, such as nerve damage caused by surgery (e.g. with electrotherapy). Psychological individual and group sessions and learning relaxation techniques can be helpful in getting to grips with psychological consequences such as anxiety, depression or dejection. Physical fitness can be increased with adapted exercise therapy. Heat packs, nutritional advice and social counseling (e.g. on returning to work) can also be part of the diverse range of rehab after kidney cancer.
Kidney cancer: how do you deal with the disease?
Kidney cancer is a serious disease. Dealing with it and the treatment demands a great deal of mental and physical strength from you as a patient. You can help at various levels to cope with this difficult time as well as possible.
Kidney cancer & nutrition
During kidney cancer treatment, your doctors will keep an eye on your nutritional status. This will enable them to take countermeasures in the event of an existing or impending nutrient deficiency. Nutritional advice or nutritional therapy can then be helpful – possibly even after treatment has been completed as part of rehabilitation.
Kidney cancer patients who suffer from kidney weakness (renal insufficiency) must pay particular attention to their own diet – either independently of the cancer or as a result of the cancer therapy. In the long term, they must be careful not to consume too much protein – breaking it down could put too much strain on the weakened kidney(s). A nutritionist can provide advice on the necessary dietary changes.
In general, kidney cancer patients should also avoid excessive alcohol consumption.
Kidney cancer & exercise
Sport and exercise are not only good for the body, but also for the soul. This is why, if possible, kidney cancer patients should start physiotherapy and exercise training during their cancer treatment. Targeted and individually adapted physical activity should be continued regularly during rehabilitation.
During rehab, patients also receive tips for future training at home.
Kidney cancer & psychological support
Many patients and their relatives have problems coping with a serious illness such as kidney cancer. The diagnosis alone can be a heavy burden. Added to this are the stresses and worries during the period of cancer treatment and aftercare.
Professional support from psycho-oncologically trained specialists can help in such cases. Such specialists focus on the mental and physical effects of cancer and help those affected to cope better.
According to experts, cancer patients and their relatives should have the opportunity to take advantage of psychosocial counseling and treatment throughout the entire illness and treatment phase. Talk to your doctor about this if necessary! They can discuss your worries and fears with you and/or put you in touch with suitable professional contacts.
Kidney cancer & complementary therapy
- Acupuncture
- homeopathy
- mistletoe therapy
- hyperthermia
If you would like to use such methods as a supplement – i.e. complementary – to conventional (“orthodox”) kidney cancer therapy, you should first speak to your doctor. He or she can advise you of possible risks and interactions.
However, they are not suitable as alternative healing methods – cancer experts strongly advise against using acupuncture etc. as a substitute for conventional kidney cancer treatment.
There are no generally established definitions for “complementary medicine” and “alternative medicine”. The two terms are sometimes used interchangeably. In general, however, complementary therapies differ from alternative therapies in that they do not question the value and approach of conventional medicine (“conventional medicine”), but see themselves as complementary to it.
