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Kidney cancer is the most common malignant neoplasm of the kidney. The first symptoms of kidney cancer often don't appear until the disease is advanced. The prognosis of kidney cancer depends on the microscopic structure of the tumor and its stage at the time of diagnosis. Find out who is at increased risk of developing kidney cancer, how kidney cancer is diagnosed and what methods are used to treat kidney cancer.

Kidney canceris the most common malignant neoplasm of the kidney. Every year, about 5,000 new cases of kidney cancer are diagnosed in Poland. Kidney cancer can develop completely asymptomatically. According to scientific studies, more than half of the cases of kidney cancer are detected accidentally during imaging tests of the abdominal cavity. Surgical removal of the tumor is the primary treatment for kidney cancer. Many new targeted drugs have been introduced to the treatment of advanced kidney cancer.

Kidney cancer - general information

The kidney is a paired bean-shaped organ, measuring approximately 10-12 cm in its longest dimension. The kidney's task is to filter the blood and remove harmful metabolic products. In addition to excreting unnecessary components into the urine, the kidney also regulates the blood composition.

Depending on the needs, it saves or removes excess water. At the same time, it affects the concentration of electrolytes: sodium, potassium, calcium as well as chloride and bicarbonate ions. The production of hormones should also be mentioned among the additional functions of the kidney.

The most famous examples of hormones produced in the kidney are renin and erythropoietin. The main role of renin is to regulate blood pressure. Erythropoietin, on the other hand, is a hormone that stimulates the production of red blood cells - erythrocytes.

When using the term "kidney cancer" we usually refer to Renal Cell Carcinoma (RCC). It is a malignant neoplasm of the kidney, originating in the tubular epithelium of the kidney. However, it is worth knowing that other malignant neoplasms can also develop in the kidney. Their example is urothelial cancer.

Within the kidneys, the pathway that carries out urine begins. They are covered with the so-called urothelial epithelium. Urothelial cancer is a cancer of the urinary tract that canalso develop in the upstream sections of the urinary tract (still within the kidney).

Malignant neoplasms of other origins, such as sarcomas and lymphomas, are much less common in the kidney. It should be emphasized that renal cell carcinoma is the most common malignant neoplasm of the kidney, accounting for approx. 85-90% of all malignant neoplasms of this organ.

Historically, kidney cancer was also called the Grawitz tumor, in memory of the German scientist - Paul Grawitz, who studied the microscopic analysis of kidney tumors. At the end of the 19th century, Grawitz developed the theory that some kidney tumors are similar in structure to the adrenal glands. According to his hypothesis, kidney cancer was called hypernephroma for many years.

This name suggested it was a tumor originating in the adrenal glands. The Grawitz theory was finally disproved - today it is known that kidney cancer is a tumor originating in the tubular epithelium of the kidneys. Nevertheless, the name "Grawitz tumor" is still used in the medical literature.

Kidney cancer - risk factors

Kidney cancer incidence accounts for about 2-4% of all malignant neoplasms in the adult population. The risk factors for developing kidney cancer include:

  • age: the risk of developing kidney cancer increases with age, and the highest incidence occurs in the 6th and 7th decade of life;
  • male gender: kidney cancer is twice as common in men as in women;
  • smoking: smoking is thought to be responsible for up to 1/3 of kidney cancer cases;
  • obesity: obesity and related metabolic disorders predispose to the development of kidney cancer;
  • hypertension: increased blood pressure is another proven risk factor for the development of kidney cancer. Maintaining blood pressure within the normal range may protect against kidney cancer;
  • environmental factors: frequent contact with certain substances (asbestos, trichlorethylene) is a factor that increases the risk of kidney cancer;
  • chronic kidney disease: end-stage renal failure requiring dialysis therapy predisposes to kidney cancer development;
  • genetic factors: approximately 2-5% of kidney cancer is genetic. There are syndromes in which kidney cancer is one of the elements of the clinical picture. Examples of such conditions include von Hippel-Lindau syndrome and Birt-Hogg-Dube syndrome.

A study by Mayo Clinic scientists published in 2022 became an interesting fact in the scientific world. It showed that regular consumption of coffee (containing caffeine) reduces the risk of getting sickfor kidney cancer. Even more intriguing, the same study found an increased risk of kidney cancer in people consuming decaffeinated coffee.

Kidney cancer - symptoms

The spectrum of symptoms of kidney cancer is very broad, and many of them may appear completely unrelated to kidney dysfunction. However, it should be emphasized that most of the symptoms of kidney cancer appear only in the late stages of cancer advancement.

The early stages of kidney cancer development do not give any indication of the disease in many cases. For this reason, a significant proportion of kidney cancer cases are diagnosed accidentally.

There are various reasons for the relatively long asymptomatic period in renal cancer. One of them is the fact that the kidney parenchyma is not innervated by the nerves. For this reason, the initial development of the tumor within the kidney does not cause pain or discomfort in the area of ​​the kidneys.

These types of symptoms do not appear until the tumor is large enough to stretch the capsule surrounding the kidney. This bag has a rich sensory innervation - it is the source of pain that occurs at a certain stage of kidney cancer development. The most common locations of pain in kidney cancer are the lumbar region and the side of the torso.

Another symptom typical for kidney cancer is hematuria, i.e. hematuria. The presence of blood in the urine can be seen with the naked eye - then we are talking about macroscopic hematuria, or macrohematuria. Sometimes only a small amount of blood gets into the urine, which can only be seen with a microscopic examination. This symptom is called microscopic hematuria, or microhematuria.

A tumor developing within the kidney can reach a size large enough that it begins to be palpable on physical examination of the kidneys. A lump may be palpable in the lumbar region or on a deep abdominal examination.

The presence of such a tumor along with the previously mentioned symptoms (pain in the lumbar region and the presence of blood in the urine) has historically been called the Virchow triad. This is a set of symptoms typical of kidney cancer.

It should be emphasized, however, that nowadays kidney cancer is rarely so advanced as to reveal all these symptoms. The Virchow triad can be found only in 5-10% of kidney cancer cases today.

The hallmark of kidney cancer is infiltration of the renal vein. The tumor grows into the lumen of the vessel, forming a plug that blocks blood flow. In some patients, the neoplastic infiltration may extend to the inferior vena cava. It is a large venous vessel that drains blood from the bottomhalf of the body. The nature of the growth of kidney cancer causes a tendency to produce stagnation in the venous circulation.

It applies in particular to the lower limbs, on which swellings may appear. A characteristic symptom in men is varicocele, especially on the left side. They are caused by blood stagnation in the left testicular vein, which is directly connected to the left renal vein.

Late stages of cancer are often associated with feelings of chronic weakness. It may be accompanied by low-grade fever, lack of appetite and weight loss. In kidney cancer, drenching night sweats may also appear ( although this is also a symptom of other cancers).

In the course of kidney cancer, the so-called paraneoplastic syndromes. These are symptoms that result from the cancer developing in the body. Neoplastic tissue is metabolically active, it can produce various hormones and influence the course of many processes in the body.

Paraneoplastic syndromes are the result of this tumor activity. They can take a wide variety of forms. In some cases, the paraneoplastic syndrome is the first symptom the diagnosis of which ultimately leads to the diagnosis of kidney cancer.

Paraneoplastic syndromes typical of kidney cancer include hypercalcaemia (increased blood calcium levels), liver dysfunction, thrombotic changes and neuropathies (disorders of the peripheral nerves). It is also worth remembering about paraneoplastic syndromes resulting from changes in the hormonal activity of the kidney. The overproduction of renin may cause arterial hypertension.

The second hormone produced by the kidney, erythropoietin, can be either over- or under-released. The first case will result in anemia (anemia - deficiency of red blood cells), and the second - polycythemia (hyperemia - an excess of red blood cells).

Kidney cancer - diagnosis

Diagnostics of kidney cancer begins with a medical history, taking into account the symptoms reported by the patient and the presence of risk factors for developing kidney cancer. In many cases of kidney cancer, physical examination does not reveal any abnormalities. In more advanced stages of cancer, the doctor may feel a tumor in the area of ​​the kidneys and the presence of pain during the examination.

Suspicion of any kidney disease is an indication for an ultrasound examination (USG) of the abdominal cavity. It is a safe and widely available study. The abdominal ultrasound is usually the first to visualize the suspecta change in the kidney.

It is also worth noting that in many patients (according to some sources, up to 60%) it is a completely accidental find. Kidney cancer is often detected during ultrasound performed for completely different indications.

Most of the ultrasound examination allows to distinguish a malignant from a benign lesion. Some features are typical of the renal cancer picture, while others are characteristic of benign tumors. Nevertheless, diagnosis based on ultrasound alone is not always possible.

In many cases, there are indications for additional imaging tests. Most often, computed tomography of the abdominal cavity and pelvis is performed. In addition to visualizing the tumor, this examination allows for a more accurate assessment of the stage and extent of the neoplastic disease.

Magnetic resonance imaging is performed a little less frequently (higher price, lower availability). It is a test that allows for precise visualization of soft tissues and - typical for kidney cancer - infiltration of the veins.

If high tumor stage is suspected and distant metastases are present, further tests may be required to find other tumor sites. The most frequently performed are: bone scintigraphy and computed tomography of the chest and head. However, these tests are not performed routinely in every patient, but only when there are clear indications for them.

The diagnosis of kidney cancer is supplemented by additional laboratory tests. Primarily, the patient's blood and urine are analyzed. In the course of kidney cancer, changes may or may not occur, such as anemia, blood in the urine, and increased calcium levels in the blood (hypercalcemia). The assessment of kidney function is also routinely performed by measuring the concentration of creatinine in the blood (its increase may indicate impaired kidney function).

The final diagnosis of kidney cancer is obtained after a histopathological (microscopic) examination of the tumor tissue. If the current diagnostic process is unsure as to the nature of the detected lesion, the physician may decide to perform a biopsy in consultation with the patient. It is a test consisting in taking a piece of neoplastic tissue for examination with a special needle.

A biopsy is not performed in all cases of kidney cancer, however. Sometimes only the material obtained during the tumor removal surgery is subjected to the histopathological examination.

Kidney cancer - classification

Proper renal cancer treatment planning requires an accurate diagnosis. Self recognitioncancer is not enough - you need to know exactly its type, microscopic structure and stage. All these parameters are described using special classifications. It is therefore worth finding out what the terms in the results of diagnostic tests mean.

The first important parameter is the histological subtype of renal cancer. This subtype tells us what kind of cells the cancer is made of. Assessment of the histological subtype is performed during the histopathological examination. On this basis, the following types of kidney cancer are distinguished:

  • clear cell carcinoma - this is the most common type of kidney cancer, accounting for approximately 75% of all cases. Clear cell carcinoma is named after the characteristic cancer cells that are filled with fat droplets that give them a bright appearance.
  • papillary cancer - is the second most common type of kidney cancer, accounting for around 15% of all cases. A characteristic feature of papillary carcinoma is the tendency to form multiple foci at the same time (or occur simultaneously in both kidneys).
  • chromophobic carcinoma - accounting for about 5% of kidney cancer cases. The hallmark of chromophobic cancer is its low mitotic index, which means that its cells divide very slowly. The risk of distant metastasis with chromophobic cancer is lower than with other types of kidney cancer.
  • other, rarer subtypes (e.g. collecting tubular carcinoma, mucous carcinoma, mixed neoplasms) - together account for the remaining 5% of kidney cancer cases.

During the histopathological examination, not only the type of cells that make up a given tumor is assessed. The test is also aimed at identifying the features of the neoplasm that may be important in treatment planning and in assessing the prognosis of a given patient.

The biological and genetic parameters are assessed, helping to predict which type of therapy will be most appropriate in a given case.

As in the case of other malignant neoplasms, a very important information when planning the treatment of kidney cancer is the stage of the disease at the time of diagnosis. The staging is assessed using the TNM classification (Tumor - Lymph Nodes - Distant Metastases: Tumor - Nodes - Metastases). The TNM classification for kidney cancer is as follows:

  • feature T - size of the primary tumor:
    • T1 - tumor ≤ 7cm in size, limited to one kidney;
    • T2 - tumor size>7cm, limited to one kidney;
    • T3 - infiltrating tumorvenous vessels or perirenal fat; the tumor does not reach the adrenal gland or cross the renal fascia (the membrane surrounding the kidney);
    • T4 - tumor infiltrating the renal fascia.
  • feature N - lymph node involvement:
    • N0 - no metastases in the local lymph nodes;
    • N1 - presence of metastases in nearby lymph nodes.
  • feature M - presence of distant metastases (in other organs):
    • M0 - no distant metastasis;
    • M1 - presence of distant metastases.

For example, if the histopathological examination of a tumor shows the mark T2N0M0, it means that the size of the tumor exceeds 7 cm, the tumor does not exceed the renal fascia, and there are no metastases in nearby lymph nodes or in distant organs.

The advancement of kidney cancer is determined on the basis of TNM features on a four-level scale (I-IV).

Stage I: T1N0M0 Stage II: T2N0M0 Stage III: T3N0M0, T1N1M0, T2N1MO or T3N1M0 Stage IV: T4N0M0, T4N1M0 or M1 feature (regardless of T and N features).

The above stages are of key importance for the assessment of the patient's prognosis.

Kidney cancer - treatment

The most important treatment method for kidney cancer is surgical removal of the tumor. The type and scope of the surgery depends on the stage of the cancer and the general he alth of the patient. In most cases, removing a kidney tumor requires nephrectomy, i.e. a kidney excision. In some situations it is possible to carry out the so-called sparing nephrectomy.

It is a procedure involving the removal of the tumor and part of the kidney, leaving a certain amount of active parenchyma of the operated kidney. Sparing nephrectomy is used primarily for small tumors. An indication for such a procedure is also a dysfunction of the second kidney, resulting in the need to save as much volume as possible in the operated kidney.

An operating procedure of a much greater extent is the so-called radical nephrectomy. In addition to removing the neoplastic tumor along with the entire kidney, radical nephrectomy also excludes other neoplastic tissues.

These can include nearby lymph nodes, the fascia surrounding the kidney, fatty tissue, or the adrenal glands adjacent to the kidney. Both conserving and radical nephrectomy can be performed from two accesses: the so-called laparotomy or laparoscopic surgery.

Laparotomy is the classic opening of the abdominal wall. Laparoscopy is a method of carrying out the procedure in a less mannerinvasive, using a camera and special tools introduced into the abdominal cavity. The choice of the procedure to be performed depends on the location and extent of the tumor, anatomical conditions and the preferences of the team performing the procedure.

Planning a kidney tumor removal surgery requires a careful analysis of the patient's he alth. There are situations in which carrying out such a large operation could be too risky for the patient.

In such cases, less invasive methods are used, including cryoablation and percutaneous ablation using radio waves. The purpose of these treatments is to destroy the tumor tissue through physical factors (low temperature or radio waves). Minimally invasive treatment techniques are also used in the treatment of very small kidney tumors.

For the treatment of advanced cases of kidney cancer (presence of distant metastases), the so-called targeted therapies. Drugs used in this type of therapy belong to the group of the so-called angiogenesis inhibitors. These are substances that block the formation of new blood vessels within the tumor.

Cancer that is unable to form blood vessels does not receive enough nutrients, so it stops growing. Drugs from the group of angiogenesis inhibitors subject to reimbursement in Poland are sunitinib and pazopanib.

An example of a drug used in the therapy of the so-called The second line of treatment is everolimus, which inhibits both tumor vascularization and the division of neoplastic cells. It is also worth noting that classic chemotherapy is ineffective in the vast majority of cases of kidney cancer.

Kidney cancer - prognosis

The prognosis of kidney cancer depends on the histological structure of the tumor and the stage of the disease at the time of diagnosis. The five-year survival rate is used to assess prognosis in oncology. It represents the percentage of patients who live at least 5 years from the diagnosis of neoplastic disease.

In the case of kidney cancer, the percentage is as high as 90% for stage I tumors, approximately 80% for stage II tumors and 60% for stage III tumors. Also for the most advanced stage IV kidney cancer, prognosis has improved in recent years thanks to the introduction of new targeted therapies.

About the authorKrzysztof BialaziteA medical student at Collegium Medicum in Krakow, slowly entering the world of constant challenges of the doctor's work. She is particularly interested in gynecology and obstetrics, paediatrics and lifestyle medicine. Language loverstrangers, travel and mountain hiking.

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Oncology