Understanding Kidney Cancer: Causes, Symptoms, and Treatment

Understanding Kidney Cancer: Causes, Symptoms, and Treatment

Kidney cancer, i.e. a tumour in the area of ​​the kidneys, often only becomes apparent at a late stage and is therefore only discovered by chance in many cases. Possible symptoms are back pain and blood in the urine or unspecific symptoms such as exhaustion, fever attacks and weight loss. Every year, around 15,000 people in Germany develop cancer in the area of ​​the kidneys and urinary tract. Older people between the ages of 60 and 75 are particularly affected, with men developing kidney cancer more frequently than women.

Kidney cancer: what types are there?

There is no “one” kidney tumour, but the cancerous tissue can be very different:

  • In the kidney area, 95 per cent of adults have renal cell carcinoma  (also renal carcinoma or adenocarcinoma of the kidney). They emanate from the cells of the urinary canal (tubule system) responsible for urine formation.
  • A unique form is an oncocytoma, which accounts for about four per cent of cases and is similar to a kidney carcinoma in imaging procedures but does not form metastases.
  • Malignant changes in the area of ​​the renal pelvis are much rarer. They do not emanate from the kidney cells but from the mucous membrane of the urinary tract. They are thus similar to the types of cancer that predominantly occur in the urinary bladder ( bladder cancer ) and the ureters. Their treatment is, therefore, different from that of renal cell carcinoma.
  • In addition, malignant tumours, which do not originate in the kidney tissue but in the muscles (sarcomas)  or lymphatic tissue lymphomas ), can develop in rare cases.
  • In children (especially children under the age of five), Wilms’ tumours (nephroblastomas) are the most common.

Due to the prevalence of renal cell carcinoma, the following article only deals with this form of kidney cancer.

Kidney cancer: causes and development

The possible causes are as diverse as the tissue of origin; however, as with other types of cancer, no specific triggers are often found. In principle, various mechanisms are conceivable, for example, physical, chemical, hormonal and infectious factors; there is also a hereditary component in kidney cancer.

In addition, some factors are known to increase the risk of kidney cancer:

  • By far, the most critical risk factor is regular smoking. The kidneys filter harmful substances out of the blood daily, including those that get into the blood when you smoke a cigarette, pipe or cigar. Constant exposure to these carcinogenic pollutants doubles the risk of developing kidney cancer. Passive smoking is also considered a risk factor.
  • High blood pressure appears to increase the risk of developing kidney cancer.
  • Another risk factor is obesity  – especially in women (probably due to the hormone shift it causes); in men, the type of fat distribution is more likely to play a role.
  • Certain lifestyle habits, such as heavy alcohol consumption, a regular high-fat diet, lack of physical activity, and not drinking enough fluids (because of reduced perfusion of the kidneys and an increased concentration of harmful substances), also appear to increase the risk of kidney cancer.
  • In addition, certain (partly congenital) diseases, such as cystic kidneys or chronic kidney dysfunction, are considered risk factors for the development of kidney cancer. Chronic kidney damage can be promoted, for example, by long-term use of painkillers.
  • The risk is also considered to be increased after a kidney transplant.
  • Substances such as halogenated hydrocarbons or cadmium (especially in occupations with high exposure to them) could also play a role. 

Kidney cancer symptoms

Unfortunately, kidney cancer symptoms often appear late, and the symptoms are then rather unspecific. The following signs should be clarified quickly by a doctor:

  • Blood in the urine: Bleeding is not always recognizable as such – sometimes, the urine is just darker than usual. Women sometimes mistakenly attribute the signs to menopause. Some bleeding cannot be detected with the naked eye but only with the help of test strips.
  • Rather, unilateral kidney pain, i.e. pain in the flank and lateral back pain, can be signs of kidney cancer, especially if a thickening is palpable in the kidney area.
  • Swollen legs can be a symptom of kidney cancer.
  • New high blood pressure or blood pressure fluctuations can indicate a kidney tumour.
  • Non-specific symptoms that persist over an extended period and for which no cause can be identified, such as constant tiredness, night sweats, persistent fever, high calcium levels, weight loss, and intestinal problems, can indicate severe but harmless chronic diseases.

Early-stage kidney cancer is often discovered by accident, for example, during an abdominal ultrasound.

How is the diagnosis made?

The first step in diagnosing kidney cancer is the anamnesis, i.e. the discussion between doctor and patient. In particular, current complaints, previous illnesses, and professional and family stresses are asked about.

After the interview, the doctor will conduct a thorough physical exam. Depending on the suspicion and the therapy planning, further tests follow. These include, for example:

  • an examination of urine and blood
  • Imaging procedures such as an X-ray examination of the urinary tract (urography), an ultrasound examination, a computer or magnetic resonance imaging ( CT and MRI ), a bone and kidney scintigraphy or an X-ray of the renal vessels
  • a cystoscopy
  • a tissue removal (biopsy)

The responsible contact person is initially the family doctor, who can then refer you to specialists such as urologists or radiologists as required.

stages of kidney cancer

To choose the proper treatment, it is necessary to determine the stage of the tumour. The classification is based on the so-called TNM classification. Crucial are:

  • the size of the tumour (T)
  • the involvement of the lymph nodes (N)
  • whether metastases have formed (M)

Based on these letters and numbers, a statement can be made about the extent and size of the tumour (T1 to 4) and whether lymph nodes are affected or metastases are present (e.g. N0 and M1)

In principle, kidney cancer is considered curable,  but this probability is significantly reduced if metastases have formed, i.e. the tumour has spread.

Renal Cell Carcinoma: What Treatments Are Available?

If the suspected diagnosis is confirmed, the primary goal is to remove altogether the tumour and any secondary tumours that may be present or – if this is not possible – to prevent the tumour from continuing to grow and spread for as long as possible. The preferred method depends primarily on the type of tumour, its size and its location.

In principle, several methods can be used individually or in combination: An operation in which the affected kidney is wholly or partially removed, an ablation, systemic therapy or radiation therapy.

  • Surgery is considered the essential form of treatment and is used when the cancer has not spread. Often, the tumour can then be removed entirely and the cancer cured. However, even after the removal of the tumour, recurrence can occur.
  • In so-called ablation, the cancerous tissue is destroyed by heat or cold. This procedure is only used for small kidney tumours and when surgery is impossible (e.g. due to old age).
  • If the tumour has spread, healing is usually not possible. So-called systemic therapy is then used to prevent the tumour from growing further and to relieve symptoms. This includes targeted therapy with drugs that attack cancer cells, immunotherapy, in which the body’s defence cells are stimulated, and supportive therapy methods that aim to alleviate the symptoms.
  • Radiation therapy is only used if the cancer has already metastasized. Radiation cannot heal.
  • Chemotherapy is not suitable for treating kidney cancer. 

It is referred to as active surveillance if (especially in older patients with previous severe illnesses and if the tumour is tiny) treatment is initially dispensed with, and the development of the tumour is further observed. Since kidney tumours usually grow very slowly in old age, in such cases, whether the patient should still be expected to accept the risks and strains of an operation is weighed.


Aftercare: What do you have to pay attention to after the treatment?

Immediately after the treatment, those affected can take part in rehabilitation (medical rehabilitation). In addition to exercise therapy and various counselling services, patients also receive psychological care there.

The person concerned must regularly attend the follow-up examinations. This is the only way to monitor the course of the disease and, in the event of a recurrence, to intervene again early or to adjust the treatment. If there are no complications, the check-up appointments occur at intervals of a few months for the first two years, then every six months and later once a year.

It is recommended to stop smoking and to lead a healthy lifestyle in general. Further measures depend on the individual clinical picture and the treatment carried out.

What is the course and prognosis?

The individual survival rate varies greatly and depends on the type and location of the malignant change and when the tumour is detected. Cancer in the kidney area often shows up very late and is often only detected incidentally during abdominal examinations in the early stages. Therefore, a general prognosis or statements on life expectancy are difficult to make.

If the tumour is caught early, while it is still limited to the kidney, the 5-year survival rate is about 70 per cent or higher if it is tiny. If, on the other hand, the lymph nodes are already affected, a 5-year survival rate of around 20 per cent is assumed. Despite this, the average survival rate is relatively high compared to many other types of cancer.

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