Kidney cancer: definition, causes, symptoms, diagnosis and treatment

By Cristiano Antonino Last updated Jun 20, 2023

Kidney cancer is the most frequent among those affecting the urinary tract, after that of the prostate and bladder

The kidneys are two symmetrical and equal organs, positioned in the lumbar area of the abdomen and have the purpose of eliminating the waste that accumulates in the body through the formation of urine.

In most cases, kidney cancer originates from the uncontrolled growth of cells in the wall of the kidney tubules that form the nephrons, structures that filter the blood from the substances that need to be expelled.

This pathology is specifically called renal adenocarcinoma and comes in different variants.

The most frequent is clear cell adenocarcinoma, then we find adenocarcinoma with granular cells, sarcomatous cells or in mixed cell form.

The least frequent carcinoma is that which originates from other structures of the kidney, such as, for example, the outer capsule.

Finally, in children, the tumor form known as nephroblastoma (or embryonic tumor) is more frequent, which originates from cells that resemble those that make up the kidney in the embryo.

Kidney cancer: what is it?

The kidneys are paired organs, positioned symmetrically in the posterior area of the abdomen and at the lumbar level.

They are the size of a fist and shaped like two beans.

Inside them there are tubular structures that have the purpose of filtering the blood by blocking the waste products that are produced by the body.

The waste substances are then expelled from the body thanks to the urine which represents the “final product” of the kidneys.

Kidney cancer originates from the uncontrolled growth of cells found in the inner walls of the tubules, but it can also derive from the capsule that covers the organ outside and from other tissues.

Kidney cancer: the spread

Kidney cancer is much more common among men and the probability of developing this pathology increases proportionally with age, reaching the maximum peak of onset in patients aged around 60 years.

According to some estimates, the risk of developing this type of cancer is 1 in 40 for men and 1 in 91 for women.

Those at risk

Kidney cancer is linked to the presence of certain risk factors that may predispose to the onset of the disease.

The most common is cigarette smoking.

From what emerges from scientific literature studies, the number of cigarettes and years of exposure to smoke are directly proportional to the increase in the risk of getting sick.

Another important risk factor is represented by chronic exposure to some metals and carcinogenic substances such as asbestos, cadmium, phenacetin and torotrast.

Obesity, alcoholism, high blood pressure and long-term dialysis are also risk factors for kidney cancer.

There are also some rather rare hereditary forms, such as von Hippel-Lindau syndrome, which is transmitted with the VHL gene.

Prevention

Prevention of kidney cancer is only possible by limiting risk factors.

Stopping smoking and limiting alcohol consumption are the first steps to prevent this disease.

The annual execution of an ultrasound of the abdomen could favor an early diagnosis of both kidney cancer and other viscera (such as liver and pancreas).

Based on the individual risk, the doctor can recommend certain tests to monitor the patient’s condition and facilitate early diagnosis.

Kidney cancer: types

There are different types of kidney cancer.

The most frequent forms are papillary cancer (types I and II), clear cell cancer and chromophobe cancer.

In 90% of cases the pathology affects only one kidney, only in 2% can it be bilateral, thus manifesting itself in both organs.

The rarest form of kidney cancer is sarcoma.

This disease originates from different tissues – in the capsule or in the structures located around the kidney – and has various forms: liposarcomas, leiomyosarcomas, rhabdomyosarcomas, angiosarcomas, fibrosarcomas.

In children, kidney cancer manifests as nephroblastoma or Wilms tumor.

Kidney cancer: symptoms

Kidney cancer can often be asymptomatic in the early stages of the disease.

Sometimes, especially in the advanced stages, it can instead present some specific symptoms.

The patient may complain of a sense of weight or pain in the lower back, blood in the urine and the presence of a palpable mass in the abdomen.

These signals are present simultaneously in only 10 percent of cases and occur when the disease is already in an advanced state.

The pathology can be associated with the appearance of non-specific systemic symptoms, such as weight loss, fever, anemia, fatigue, detection of hypercalcaemia and hypertension.

Among the complications that may appear is varicocele, i.e. the dilation of the veins of the scrotum and testicle, due to the compression of the spermatic vein by the tumor mass.

Kidney cancer can lead to metastases, which spread through regional blood vessels and lymph vessels.

In 55% of cases the metastases are located in the lymph nodes and lung, in 33% of cases they are located in the liver and bones, in 19% in the adrenal gland and in 11% in the contralateral kidney.

However, kidney cancer can also metastasize to the brain, colon, spleen, and skin.

How is the diagnosis made?

Diagnostic imaging is essential for the diagnosis of kidney cancer, because the presence of blood in the urine and the clinical examination can be non-specific and allow the disease to be identified only late.

Through ultrasound, the doctor can identify the presence of a solid mass, distinguishing it from a cyst.

Computed tomography (CT) or magnetic resonance imaging (MRI), in addition to distinguishing the nature of the mass, offer further information on the local extension of the disease and on the presence of any metastases.

Evolution and classification of the stage of the pathology

Once the diagnosis has been made, it will be important to stage the tumor, i.e. to define the location and extent of the tumor in the kidney, as well as the involvement of other organs and structures.

To describe the pathology, an international classification is used which is based on the TNM system or that of Robson.

There is also a classification based on the stage of severity.

stage I: the tumor is limited to the area of the kidney and has a maximum diameter of 7 cm;

stage II – the tumor is located only on the kidney, but less than 7 cm in diameter;

stage III: the tumor has lymph node metastases;

Stage IV: The cancer has spread to nearby organs, has gone beyond the fatty tissue around the organ, or has metastasized from a distance.

Kidney cancer: therapy

Kidney cancer is usually treated with radical surgery that involves removing the entire affected organ.

Partial surgery is applied only when there are small tumors confined to the kidney.

In these cases, the tumor is removed, leaving the rest of the organ intact.

In patients with bilateral disease or intrarenal neoplasms, ablation of the renal mass by cryotherapy is often performed.

If the renal tumor is already metastatic, it is possible to intervene with the elimination of the diseased kidney (cytoreductive surgery), associated with systemic therapy.

Another widespread treatment consists in blocking angiogenesis, i.e. the formation of blood vessels that feed the kidney tumor: some patients could benefit from a pharmacological treatment with the anti-VEGF monoclonal antibody.

Survival rate

The survival rate of patients with kidney cancer depends on the extent of the disease at the time of diagnosis, the grade of the tumor and the patient’s general health.

The grade of the tumor is established after examining the cells exported from the diseased kidney tissue under a microscope.

Grades range from 1 to 4, the latter indicating a greater likelihood that the cancer will develop and spread rapidly.

Survival is then influenced by other key factors such as age and is reported in terms of ten-year, five-year or one-year survival rates.

Those diagnosed with stage 1 cancer have a good chance of being cured if they get treatment right away, and the survival rate is around 90%.

In case of stage 2 kidney cancer, the survival rate is between 65% and 75%.

If the diagnosed cancer is stage 3 the survival rate is between 40% and 70%.

If you are diagnosed with stage 4 kidney cancer, the survival rate drops to 10%.

Since it does not generate specific symptoms in its initial stages, this disease is often diagnosed when it is already in an advanced stage and unfortunately this can negatively affect the patient’s life expectancy.

Therefore, it is reiterated that early diagnosis plays a fundamental role.

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