Kidney cancer (renal cell carcinoma, also known as renal carcinoma or adenocarcinoma of the kidney) is a malignant tumor that usually originates in the cells of the urinary ducts (tubular system). This form is present in 95% of kidney cancer cases.
Usually only one kidney is affected. Very rarely, at just under 1.5%, both kidneys are affected. This is mostly due to genetics.

Kidney cancer is a relatively rare tumor disease. In Germany, around 15,500 people develop this tumor every year, men are affected somewhat more often than women (as of 2012). Younger people are less likely to get it, and kidney cancer is particularly often diagnosed between the ages of 60 and 70. Renal cell carcinoma accounts for about three percent of all solid malignant tumors.

Kidney cancer rarely causes symptoms in its early stages. However, if the tumor grows, pain in the flank and back can occur. Another sign of kidney cancer can be blood in the urine. Rarely, tumors can be felt in the kidneys. In men, a varicose vein rupture in the testicles can be caused by a kidney tumor.

If the complaints or symptoms such as unwanted weight loss, lack of appetite, fatigue, fever or anemia occur, this can also indicate cancer.

Kidney cancer is usually diagnosed at an early stage these days. Kidney tumors are often discovered during another examination using ultrasound in the abdomen. In order to be able to detect a kidney tumor, various physical examinations and laboratory tests are necessary. Imaging methods such as ultrasound or computed tomography (CT) are also used.

Further methods such as X-rays, magnetic resonance imaging (MRT) or skeletal scintigraphy (bone scintigraphy) may be necessary to obtain a reliable diagnosis and, if necessary, to determine the extent of the tumor, for example with bone metastases. If a kidney tumor is discovered at an early stage, the chances of recovery are usually good, whereas the prognosis for an advanced tumor stage is rather unfavorable.

Various methods are available for the treatment of renal carcinoma. If the tumor is limited to the kidney, the following treatment methods can be considered.

Surgery
If kidney cancer is diagnosed, surgery has been the standard procedure so far. If the tumor is discovered at an early stage and its size is limited, or if the other kidney is damaged or has already been removed, the operation is performed to preserve the kidneys. This is referred to as a partial kidney resection or partial nephrectomy. Usually, however, the entire kidney is removed during surgery, for example when the tumor has affected the entire kidney (simple nephrectomy). If the tumor is larger, the cancer cells can also be present in the neighboring tissue. Then the adrenal gland and surrounding lymph nodes are also removed (radical nephrectomy).

Systemic forms of therapy Chemotherapy, systemic therapy or immunotherapy
Various methods can be used systemically for renal carcinoma. However, chemotherapy alone is often not very effective in the case of a kidney tumor, since the tumors are often resistant to these drugs. Therefore, combination therapy must be used in order to achieve a successful treatment. The field of therapy can be expanded with available newer active substances, some are still in the test phase. As part of drug therapy, so-called tyrosine kinase inhibitors can also block the processes of proliferation and contribute to the regression of a tumor. Generally, the filed of immunotherapy and targeted therapy is evolving fast and recent studies show very promising results.

Active Surveillance
In older patients at an early tumor stage, under certain conditions such as age and comorbidities or limited life expectancy, the strategy of active surveillance can be selected as an alternative to surgery (active surveillance strategy). However, to minimize the risks of uncontrolled tumor growth, close monitoring with imaging every three months is necessary. If the tumor enlarges due to sudden growth, the risk for the patient can increase.

Conventional irradiation
The cells of a kidney tumor are usually less sensitive to radiation than cells of other tumors. Conventional radiation therapy, which is often administered in fractions over several weeks, is therefore usually ineffective.

Radiosurgery
Radiosurgery is a very precise irradiation of the tumor with a mostly single, high dose. A tumor is effectively destroyed by this very effective treatment method. Healthy surrounding tissue, on the other hand, is protected as much as possible. The effectiveness of treating kidney tumors with radiosurgery (e.g. Cyberknife therapy) has been shown its efficacy in scientific publications. The radiosurgical method is comfortable fand safe or patients.