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Kidney cancer: cause, symptoms, therapy

by Josephine Andrews
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Kidney cancer (malignant kidney tumor) is a malignant growth of the kidney. It can come from different cell types. Renal cell carcinoma (kidney cell cancer) is by far the most common in adults. Most patients are elderly and male. Here you can read everything you need to know about the topic: causes, symptoms, diagnosis, treatment and chances of recovery for kidney cancer.

ICD codes for this disease:

ICD codes are internationally valid codes for medical diagnoses. They can be found, for example, in doctor’s letters or on certificates of incapacity for work.

C64 C65

quick overview

  • What is kidney cancer (kidney carcinoma)? A malignant tumor of the kidney , 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: tiredness, fever, lack of appetite, weight loss, anemia, high blood pressure and signs of metastases such as bone pain, shortness of breath, headaches, etc.
  • Causes : Not exactly known. Risk factors include smoking, obesity, high blood pressure, end-stage renal failure, genetic predisposition and advanced age.
  • Diagnostics : doctor-patient discussion, physical examination, laboratory tests, imaging ( ultrasound , computed tomography, magnetic resonance imaging), if necessary biopsy . Further studies on tumor spread.
  • Therapy : If possible surgical removal. In the case of a small tumor, if necessary, only active monitoring or ablative therapy (eg destruction with cold). In advanced stages, as an alternative or in addition to surgery, drug therapy, radiotherapy .
  • Prognosis : Relatively good if kidney cancer is detected and treated early. However, if there are already kidney cancer metastases, the life expectancy (chance of survival) of those affected is significantly lower.

What is kidney cancer?

Kidney cancer (kidney carcinoma) is a malignant tumor of the kidney. It develops when individual cells of the kidney change malignantly (degenerate) and start to proliferate unchecked. Such a kidney cancer tumor can develop from different cell types.

By far the most common variant in adults is renal cell carcinoma (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: the so-called clear cell carcinoma is by far the most common; Papillary carcinoma and Ductus-Bellini carcinoma are less common.

This article primarily relates to renal cell cancer!

In addition to renal cell carcinoma, other malignant renal tumors also fall under the term renal cancer. This includes, for example, the rarer renal pelvis carcinoma . It develops from the tissues of the urinary tract, which originate at the kidneys.

In children, it is not renal cell carcinoma but what is known as nephroblastoma (Wilms tumor) that is the most common form of malignant kidney tumor. It arises from cells that resemble the kidney cells in the embryo, which is why it is called an embryonic tumor. Overall, however, children only rarely develop a malignant tumor in the kidney.

renal metastases and renal cancer metastases

In some cases, a malignant growth in the kidney turns out not to be kidney cancer but to be a metastasis from another type of cancer elsewhere in the body. Such kidney metastases can be caused, for example, by lung cancer or breast cancer.

Kidney cancer metastases , on the other hand, are daughter metastases of kidney cancer in other parts of the body. They develop when individual cancer cells detach from the tumor, reach other places via the lymphatic and blood vessels , settle there and form a daughter tumor. Kidney cancer can affect lymph nodes and cause metastases in the lungs , bones, liver or brain , 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 with the urine it produces.

In addition, the kidneys 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 blood pressure regulation) and erythropoietin (involved in the regulation of erythrocyte production).

You can find out more about these tasks of the kidneys in the article on kidney function .

Kidney cancer: frequency

Kidney cancer – by far the most common variant of which is 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 year, kidney cancer accounted for almost 2.9 percent of all new cancer cases* (489,178).

* “New cancers” means all new cases of malignant neoplasms (including leukemia and lymphoma) – with the exception of new cases of “white” skin cancer (non-melanotic skin cancer). It is international practice not to include this in “total cancer”.

How do 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 formed metastases in more distant regions: Kidney cancer then often causes blood in the urine ( hematuria ) and pain in the kidney area or pain in the flanks . In some patients, the tumor is palpable .

Common symptoms of kidney cancer include fatigue, fever, loss of appetite and unwanted weight loss. However, these symptoms are very unspecific – they can also appear in other forms of cancer and many other diseases.

Other possible kidney cancer symptoms are high blood pressure (hypertension), anemia (anemia) and an increased level of calcium in the blood (hypercalcaemia). Liver dysfunction with an increase in alkaline phosphatase (AP) in the blood is typical of renal cell carcinoma – called Stauffer syndrome .

Another sign of kidney cancer can appear in male patients: If the tumor invades one of the renal veins, a varicose vein rupture in the testicles ( varicocele ) can develop.

Metastatic kidney cancer: symptoms

If the kidney cancer has spread in the body, other symptoms generally appear. A few examples: Pain and spontaneous fractures are possible signs of bone metastases, ie skeletal involvement by the malignant kidney tumor. Symptoms of lung metastases may include shortness of breath and chest pain. Brain metastases can manifest themselves, for example, with headaches, nausea, vomiting, paralysis or seizures.

Kidney cancer: causes and risk factors

The causes of kidney cancer and kidney cell cancer are still largely unknown. However, there are certain risk factors that favor the onset of the disease. These include:

  • tuxedo
  • overweight
  • high blood pressure
  • End-stage renal failure : This is stage 5 (end-stage) chronic kidney failure. Possible causes include kidney damage from diabetes or high blood pressure, and polycystic kidney disease (a genetic condition in which numerous fluid-filled cavities form in the kidneys).
  • Genetic predisposition : in rare cases, hereditary gene mutations contribute to the formation of renal cell cancer (hereditary renal cell carcinoma). The most common 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 often occur in old age (eg cardiovascular diseases).

Some experts also classify occupational exposure to halogenated hydrocarbons or long-term X-ray radiation as risk factors for kidney cancer (kidney cell cancer risk factors).

Influence of diet unclear

The connections between dietary factors and the risk of renal cell cancer are contradictory. There is also no evidence that fruit and vegetable consumption could prevent tumor development. 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 (kidney cell cancer) is being discovered more and more by accident: During examinations that are carried out for other reasons (eg ultrasound examination or computed tomography of the abdomen), the malignant kidney tumor is found in many patients. It is often still quite small, ie not very advanced.

In other cases, the kidney cancer diagnosis is only made when symptoms of the more advanced tumor prompt the affected person to see a doctor.

History and physical examination

In the case of unexplained symptoms, the medical history is routinely first collected (anamnesis): the doctor asks exactly what symptoms the patient has, how severe they are and how long they have existed. He also asks about any previous or underlying illnesses.

The next step is the physical examination . This includes palpating the kidneys from the outside – the doctor may be able to identify a hardening or tumor.

However, further tests are required to diagnose kidney cancer. There are also examinations that can be used to determine the extent of the cancer (eg the presence of metastases). This is important for therapy 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 .

In addition, the urine is examined for blood (hematuria). Sometimes this amount of blood is so large that the urine is visibly reddish (macrohematuria). In other cases, there are not visible amounts of blood in the urine (microscopic hematuria).

imaging procedures

If the kidney tumor is of a certain size, it can usually be detected in an ultrasound examination (sonography) . Computed tomography (CT) offers a significantly higher image resolution . It is the standard method 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.

In some cases, another high-resolution imaging method is chosen as an alternative to CT – magnetic resonance imaging (MRI) , also known as magnetic resonance imaging . It is recommended, for example, if there is a suspicion that a renal cell carcinoma has already grown into veins or the vena cava. Then the spread of the tumor can be better assessed using MRI than using CT.


Imaging is usually sufficient to diagnose kidney cancer (kidney cell cancer) with certainty. However, if the diagnosis is still unclear afterwards, it is possible to take a tissue sample and examine it under the microscope (biopsy). However, this should only be done if the choice of therapy depends on the result 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, no tissue sample should 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 therapy for an unclear kidney tumor. In addition, a biopsy should or can be carried out in the following cases to confirm the diagnosis:

  • before an ablative therapy – ie before the targeted destruction of the tumor tissue by means of 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 escaping into healthy tissue during sample collection and thus spreading tumor cells.

Conducting the biopsy

The biopsy should be performed as a punch needle biopsy. Under ultrasound or CT control, a fine hollow needle is “shot” with a punch through the abdominal wall into the tumor tissue in a targeted manner 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 investigations

Once the diagnosis of kidney cancer (kidney cell cancer) has been made, it is important to find out how far the cancer has spread in the body (spreading diagnostics). Which examinations are necessary and useful for this depends on the individual case.

For example, a computed tomography of the chest (thoracic CT) should be performed on all symptom-free patients whose kidney tumor is larger than three centimeters. The larger the tumor, the greater the likelihood of metastases, for example in the lungs.

If brain metastases are suspected (eg 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 medium before the examination.

If there are possible signs of bone metastases (eg pain), the patient’s entire body is examined using CT or MRI (whole-body CT or MRI).

Occasionally, a vascular X-ray (angiography) is performed – not to record the spread of kidney cancer in the body, but to determine the vascular supply of the tumor. This can be helpful for the subsequent surgical removal of the tumor.

Kidney cancer: therapy

The tumor stage has the greatest impact on the type of treatment for kidney cancer. The patient’s age and general state of health are also taken into account when planning therapy.

In principle, a locally limited (non-metastatic) renal cell cancer is operated on if possible: if the malignant tumor can be completely excised, the renal cancer is curable. In the case of a small kidney tumor, active surveillance or ablative therapy can also be chosen as an alternative to surgery in certain cases.

In the case of renal cell carcinoma with metastases , it is usually no longer possible to heal it – ie no curative therapy aimed at healing. Instead, people with end-stage kidney cancer receive palliative therapy. This aims to prevent or alleviate symptoms, improve the patient’s quality of life and prolong his life. Various treatment options are available for this.

For example, the tumor on the kidney and the individual metastases can be treated locally, using surgery and/or radiotherapy. There are also medications available to treat kidney cancer that affect the whole body (systemic therapy).

In the following you will find more detailed information on the various therapeutic approaches for renal cell cancer.

Active Surveillance

In the case of a small renal cell carcinoma that has not yet formed metastases, therapy may be limited to active surveillance. This consists of regular check-ups in which the tumor growth is checked using imaging methods.

Such active monitoring can be useful in patients for whom surgical tumor removal or other forms of cancer therapy would be too stressful – for example in patients with other diseases 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.

When an actively monitored tumor grows, experts recommend surgical removal.

ablative therapy

A possible alternative to active surveillance in patients with small renal cell carcinoma and additional diseases and/or limited life expectancy is ablative therapy. This means the direct destruction of the tumor tissue without major surgical intervention. This is usually done using cold (cryoablation) or heat (radiofrequency ablation):

  • Cryoablation : The doctor inserts a cryoprobe into the renal cell carcinoma through a small incision in the abdominal wall or during a laparoscopy. The probe cools the tumor tissue down to -60 to -70 degrees Celsius, after which it dies.
  • Radio frequency ablation (RFA) : Here, too, a probe is inserted into the kidney tumor via the abdominal wall or during a laparoscopy. Using alternating current, it heats the cancerous tissue to between 60 and 100 degrees Celsius, destroying it.

In both cases, the insertion and “work” of the probe are monitored on a screen using imaging techniques (such as ultrasound or CT).

Operation: Various 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. If possible, an organ-preserving operation is performed ( partial nephrectomy ): the surgeon cuts out only the part of the kidney affected by the cancer. He makes sure to preserve as much healthy kidney tissue as possible.

The procedure is usually performed as an open operation , ie via a longer skin incision (depending on the location of the tumor, for example on the stomach or on the flank).

A surgeon with sufficient experience can also perform the partial removal of the kidney as part of a laparoscopy. Because this only requires several small incisions in the abdominal wall, through which the surgical instruments are inserted into the abdominal cavity, it is also referred to as keyhole surgery or minimally invasive surgery.

A non-metastatic renal cell carcinoma cannot always be removed in such a way that the rest of the kidney is preserved. Then 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, they can be surgically removed to check for cancer cells. If the imaging tests before the operation or during the operation indicate that an adrenal gland is also affected by cancer, this is also removed.

Metastatic kidney cancer: surgery

If renal cell cancer has already spread to other organs, it is no longer possible to cure it by surgical removal. Nevertheless, in some cases it can make sense to excise the malignant kidney tumor. This can, for example, relieve discomfort such as local pain and bleeding. Surgery may even extend a patient’s survival.

systemic therapy

In the case of advanced and/or metastatic renal cell cancer, anticancer drugs are usually given that act throughout the body (ie systemically). The following substance groups are available:

  • Tyrosine kinase inhibitors (e.g. axitinib, sorafenib): They inhibit signaling pathways in the cancer cells that control their growth. They also block the formation of new blood vessels that the tumor needs to grow. Overall, the kidney cell cancer can be prevented from growing at least for a while.
  • 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 limit this proliferation of cancer cells.
  • Checkpoint Inhibitors : Immune checkpoints are control points of the immune system that limit immune reactions (eg against the body’s own cells) when necessary. Some cancer tumors (such as kidney cancer) can activate these “brakes” and thus protect themselves from the attack of the body’s defenses. 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 to supply it.

Doctors decide on a case-by-case basis which drugs are most suitable for a kidney cancer patient. Drugs 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 here with interferon – an active ingredient that counteracts the growth of cancer cells.

Depending on the active ingredient, the medication is used, for example, in the form of infusions or tablets. During systemic kidney cancer treatment, the course of the disease should be checked every six to twelve weeks using a detailed imaging examination (preferably computer tomography).

The “classic” drug treatment for most forms of cancer is chemotherapy. However, it is not a treatment option for kidney cancer – ie metastatic renal cell cancer – because it usually has no effect here.

Local treatment of renal cancer metastases

Kidney cancer metastases (lungs, bones, etc.) are often treated in a targeted manner. The goal 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 (radiation therapy) can be used. Under certain circumstances (e.g. in the case of some brain metastases) the latter can also be carried out as stereotactic radiotherapy. 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 cancer or cancer therapy are treated in a targeted manner. Examples:

Painkillers (analgesics) help against tumor-related pain . For mild pain, paracetamol or ibuprofen may suffice. For moderate pain, the doctor will prescribe a mild opioid pain reliever, such as tramadol . In the case of severe tumor pain, potent opioid painkillers such as morphine must be used.

This pain therapy can sometimes be 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 severe exhaustion (fatigue). On the other hand, experts recommend individually adapted endurance training as part of exercise therapy .

Kidney cancer patients with bone metastases should be given medications to prevent bone fractures – bisphosphonates or the monoclonal antibody denusomab in combination with calcium and vitamin D.

Kidney cancer: disease course and prognosis

Most of those affected 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 the size of the kidney tumor and how far it has spread at the time of diagnosis. The following applies here: The earlier diagnosis and treatment take place, the better the prognosis for kidney cancer.

On the other hand, chances of recovery and life expectancy also depend on the type of kidney cancer. As already mentioned, the vast majority of patients have renal cell cancer, namely the clear cell type. This tends to have a slightly poorer prognosis than other localized-stage renal cell carcinoma types while it is still limited to the kidney.

The age of the patient and any concomitant diseases also have an influence on the chances of recovery from kidney cancer (kidney cell cancer).

Kidney cancer: aftercare and rehabilitation

Even after the end of the kidney cancer treatment, the patients are not left alone. Aftercare and rehabilitation are the next steps.


Participation in the recommended follow-up examinations after kidney cancer are very important. The check-up appointments serve, among other things, to detect a possible recurrence (recurrence) of kidney cancer and (new) metastases at an early stage. It is also important to keep an eye on the patient’s kidney function.

The follow-up examinations routinely include a doctor-patient interview (anamnesis), physical and laboratory examinations as well as an imaging examination of the abdomen and, if necessary, also the chest (ultrasound and/or computed 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). Basically, several follow-up appointments over a period of several years are recommended. Initially, they are set at shorter intervals (e.g. every three months), later at greater intervals (annually).

Kidney cancer rehabilitation

After kidney cancer, individually tailored rehabilitation (rehab) is recommended. It is intended to help patients to cope with the consequences of the disease and its treatment and to become physically and mentally fit again for the return to everyday life and possibly working life.

What the rehabilitation program looks like in detail depends on the needs of the patient. However, building blocks from a wide variety of disciplines are incorporated, for example from medicine, psychology, physiotherapy , ergotherapy and sports therapy.

Doctors in rehabilitation take care of existing side effects of cancer therapy, such as nerve damage caused by surgery (eg with electrotherapy ). Psychological individual and group discussions and learning relaxation techniques can be helpful in order to get mental consequences such as anxiety, depression or dejection under control. Physical fitness can be increased with appropriate exercise therapy. Heat packs, nutritional advice and social counseling (eg on returning to work) can also be part of the diverse range of rehabilitation after kidney cancer.

Kidney cancer: how to deal with the disease?

Kidney cancer is a serious disease. Dealing with it and the treatment demand a lot of mental and physical strength from you as a patient. You can help on different levels to get through this difficult time as well as possible.

Kidney Cancer & Nutrition

A special diet is generally not necessary for kidney cancer. However, a healthy, balanced diet with sufficient drinking is generally advisable to promote general health and support the immune system. This can also help to better cope with the often stressful cancer therapy.

During kidney cancer treatment, your doctors will monitor your nutritional status. In this way, they can take countermeasures in the event of an existing or impending nutrient deficiency. Nutritional counseling or nutritional therapy can then be helpful – possibly even after the end of treatment as part of rehabilitation.

Kidney cancer patients who suffer from kidney weakness (kidney insufficiency) must pay particular attention to their own diet – either independently of the cancer or as a result of cancer therapy. In the long term, you 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 making the necessary dietary changes.

In principle, 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. That is why, whenever possible, care is taken to ensure that kidney cancer patients start physiotherapy and exercise training during cancer therapy. In rehabilitation, targeted and individually adapted physical activity should be continued regularly.

For example, exercise therapy based on endurance, strength and/or coordination can be useful. Activities such as swimming , Nordic walking and treading water can also increase physical fitness and build up muscles that were lost as a result of kidney cancer and therapy.

During rehabilitation, 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. Just being diagnosed can be a heavy burden. Then there are the burdens and worries during the time of cancer therapy and aftercare.

Professional support from specialists trained in psycho-oncology can help in such cases. Such specialists focus on the mental and physical effects of cancer and help those affected to deal with it better.

According to experts, cancer patients and their relatives should have the opportunity to take advantage of psychosocial counseling and treatment throughout the entire disease and therapy phase. Speak to your doctor if necessary! He can discuss your concerns and fears with you and/or put you in touch with suitable professional contacts.

Kidney Cancer & Complementary Therapy

Some patients with kidney cancer hope for the additional help of complementary healing methods. They can improve well-being and quality of life and generally strengthen body and soul. As a rule, however, they cannot do anything against the cancer itself. Some examples of such procedures sometimes used for kidney cancer (cancer in general):

If you would like to use such methods as a supplement – ie complementary – to conventional (“orthodox medical”) kidney cancer therapy, you should first speak to your doctor. He can point out possible risks and interactions to you.

However, they are not suitable as alternative healing methods – cancer experts strongly advise against using acupuncture & Co. 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 synonymously. In general, however, complementary therapies differ from alternative therapies in that they do not question the value and approach of conventional medicine (“orthodox medicine”), but see themselves as a complement to it.

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