Renal cancer: Get informed

What is kidney cancer?

Definition

Kidneys are organs that filter blood and produce urine. They eliminate waste and maintain the balance of water and minerals necessary for the body.

Kidney cancer is the development of a malignant tumor in the kidney.

A tumor develops due to the transformation of an initially normal cell, which starts multiplying randomly to form a cell mass called a cancerous tumor.

There are two main types of renal cancer, those originating from cells of renal tissue: renal cell carcinomas, representing 90% of renal cancers and mainly affecting a single kidney, and other renal cancers (nephroblastic, metanephric tumors, etc.) which affect both kidneys in 40% of cases and require specific treatments.

Is kidney cancer common?

Kidney cancer accounts for about 3% of all cancers.

In the USA about 76,080 new cases of kidney cancer (48,780 in men and 27,300 in women) will be diagnosed in 2021. Men are affected almost twice as much as women. The average age of people when they are diagnosed is 64 with most people being diagnosed between ages 65 and 74.

The number of new cases has increased slightly in recent years, certainly due to the aging of the population and earlier diagnoses made using medical imaging techniques to detect cancers that were not detectable at this stage before.

Mortality rates are declining, in particular due to the fact that treatment has changed significantly in recent years. The estimated 13,780 people (8,790 men and 4,990 women) will die from this disease in the US in 2021.

The prognosis for this cancer is generally good with a relatively high recovery rate. Currently, the 5-year survival rate (number of people alive 5 years after diagnosis) is about 75%.

However, the prognosis is different depending on the grade and stage of the disease at the time of diagnosis. Cancer diagnosed early enough (at a localized stage) will have a better prognosis than cancer diagnosed at a later stage.

In more than half of the cases, kidney cancer is diagnosed at a localized stage with a good prognosis.

Symptoms and complications of renal cancer

As with most cancers, during the first years kidney cancer is asymptomatic. Symptoms usually appear when cancer has moved to an advanced stage.

Symptoms that may be seen in kidney cancer are:

• Presence of blood in the urine (hematuria). When this symptom is present, the urine is coloured in red (contains blood), during the entire process of urination, and it happens all the time;
• Lower back pain, especially at the side, with a possible presence of a palpable mass;
• General and non-specific symptoms, such as general health deterioration, manifested by general fatigue (asthenia), unexplained fever and / or weight loss;
• Swelling in legs and phlebitis may also be observed, as well as the enlarged testicular vein  in older men;
• Other symptoms can be seen, caused by the presence of metastases. Coughing and shortness of breath are often observed in case of metastases to the lungs, which is the most common area with metastases from kidney cancer. However, metastases can also be localized in bones, liver or brain, for example.

It is a slow-growing cancer, however it tends to migrate rapidly to other parts of the body, which results in metastases present in 20% of kidney cancers at the time of diagnosis.

Causes and risk factors for renal cancer

The main risk factors for kidney cancer are:

• Chronic kidney disease, the main risk factor for a 7-fold increase in the risk of developing kidney cancer. A special follow-up care will be set up for these patients, as well as for patients who have undergone kidney transplantation, in order to monitor the possible development of kidney cancer;
• Smoking: tobacco consumption significantly increases the risk of developing kidney cancer. However, this risk would be reduced by 25% to 30% in people who have not been smoking for about 10 to 15 years, compared to current smokers;
• Excess weight and obesity: in fact, recent studies have shown that the higher the BMI, the higher the risk of developing kidney cancer, knowing that an increase in BMI of 5 kg / m² would increase the risk of developing kidney cancer by 24 to 34%;
• Dialysis treatment lasting for more than 3 years, can trigger the appearance of renal cysts, increasing the risk of developing kidney cancer by 30 times, compared to the general population.

More rarely, a genetic predisposition can be the cause of kidney cancer. In this case, it is a hereditary, or family form. These forms represent 1 to 4% of kidney cancers with an earlier age of onset than for non-hereditary forms. In the case of kidney cancer that has occurred in your family, it is essential to organise regular monitoring visits, the risk of this cancer being multiplied by two when it is diagnosed in a first-degree member of your family. 

Other risk factors are possible, such as high blood pressure, not controlled by treatment, as well as repeated exposure to cadmium or asbestos.

Diagnosing renal cancer

In the majority of cases, kidney cancer is discovered incidentally during an ultrasound or abdominal scan done for some other reason. However, further testing is needed to rule out other forms of tumors, including benign kidney tumors.

To establish the diagnosis, a clinical examination will be performed as well as a CT scan of the abdomen, a reference examination used to diagnose the disease and assess the extent of the tumor.

The tumor will then be microscopically studied after being removed surgically, to confirm the diagnosis.

These examinations will determine the nature of the tumor, the stage (extent) and the grade (capacity for progression) of the cancer.

To determine the stage of cancer development, a special classification is commonly used: the TNM staging system. It takes into account the size of the tumor (T), the presence or absence of cancer cells in the lymph nodes (N) and the presence or absence of metastases (M).

TNM staging system for renal cancer

T (Tumor):

• Tx: Primary tumor cannot be assessed
• T0: No primary tumor
• T1: Tumor confined to the kidney and is < 7cm, where:
  • T1a: < 4 cm
  • T1b: > 4 and < 7 cm
• T2: Tumor confined to the kidney  and is > 7cm
• T3:
  • T3a invasion of perirenal fat and / or of the adrenal gland
  • T3b invasion of the renal vein and / or of the subdiaphragmatic vena cava
  • T3c invasion of the supra-diaphragmatic vena cava
• T4: Gerota fascia crossing

N (Invasion of the regional lymph nodes):

• Nx: Lymphadenopathy cannot be assessed
• N0: No lymph node metastases
• N1: Metastases in one lymph node
• N2: Metastases in several lymph nodes

M (Distant metastases):

• Mx: Distant metastases cannot be assessed
• M0: No metastases
• M1: Distant metastases present

Based on this TNM classification, the stage of the tumor is determined as follows:

Stage I: T1N0M0 (T1a/T1b)
Stage II: T2N0M0
Stage III: T3N0M0 (T3a/T3b/T3c) or T1/T2N1M0
Stage IV: T4N0M0 or all T/N1-N2/M0 or all T/allN/M1

Treatment for renal cancer

As for any other type of cancer, treatment plan is established for each patient according to the circumstances of their diagnosis (nature of the tumor, stage of the disease, age of the patient, etc.).

The choice of treatment will be made during a multidisciplinary meeting, which brings  together different specialists to determine the most appropriate treatment. Certain criteria, such as general condition of the patient (able or not to withstand surgery, for example), the type of cancer (localised or metastatic) as well as the risk of tumor progression may be taken into account to determine the best treatment plan.

Surgery:

When cancer is localised or locally advanced, the treatment consists of removing the tumor.

Two types of surgeries can be performed: partial nephrectomy (removal of the kidney) and total nephrectomy.

Partial nephrectomy is nowadays the gold standard. It makes it possible to only remove the tumor, and keep the rest of the kidney. This technique is usually preferred (if possible), to allow the patient to preserve their renal function. It is also used when both kidneys are affected or if the patient has only one kidney.

This surgery lasts on average for 2 to 5 hours, and is performed under general anesthesia.

Total nephrectomy, which is the complete removal of the kidney, is performed when partial removal is not possible, or in the case of more advanced kidney cancers. Total nephrectomy is called extended when the kidney and surrounding fatty tissue are removed.

Ablative treatments:

In the case of contraindication to surgery, or of a small tumor in elderly patients or patients with comorbidities, so-called ablative treatments can be used, such as radiofrequency treatments (destruction of the tumor by heat) or cryotherapy / cryoablation (destruction of the tumor by cold).

Radiofrequency consists of the introduction (through the skin) of a probe into the tumor. This technique will allow cell death by coagulation of the tumor.

Cryotherapy is performed through the introduction of needles by means of a puncture, under scanner control. As this method uses the cold, cell death will be obtained by freezing.

Medication:

For metastatic cancers, treatment will mainly be based on drugs (immunotherapy or targeted therapies), whether or not associated with surgery.

Immunotherapy

Immunotherapy is a therapeutic approach that stimulates the patient's immune system to fight the disease and, in the case of cancer, to destroy the tumor.

This therapeutic strategy therefore does not directly target the tumor, but acts by stimulating  the immune system.

Several immunotherapies are used in the treatment of advanced forms of kidney cancer, the two main ones being interferon alpha and interleukin 2. These two proteins are cytokines made by lymphocytes (white blood cells) and are involved in the defensive reactions of the body. They are administered  via a subcutaneous injection and stimulate the immune system so that it destroys cancer cells.

Targeted therapies

Targeted therapies act in a specific way, by blocking the growth of cancer cells or the growth of blood vessels that nourish the tumor, allowing it to supply itself with nutrients and oxygen.

This approach therefore prevents the development of the tumor by controlling its growth or  the blood vessels which provide the essential elements for its growth.

3 types of targeted therapies are used to treat kidney cancer:

• Vascular endothelial growth factor inhibitors VEGF
• Tyrosine kinase inhibitors
• MTOR enzyme inhibitors

Vascular endothelial growth factor inhibitors VEGF block the growth of blood vessels (= angiogenesis) supplying the tumor. Lacking nutrients and oxygen, the tumor will no longer be able to grow.

Tyrosine kinase inhibitors also block angiogenesis (growth of blood vessels) by inhibiting receptors for different blood vessel growth factors.

MTOR (mammalian target of rapamycin) enzyme inhibitors block the enzyme involved in the regulation of cell growth, cell proliferation, etc. In cancerous processes, mTOR goes out of order and enables the growth of cancer cells. Thus, blocking this enzyme will prevent the uncontrolled proliferation of cancer cells.

Other treatments

Because kidney cancer cells are generally resistant to conventional chemotherapy, it is not used in treating kidney cancer. Radiation therapy is also rarely used.

Palliative care plan can be set up to alleviate the consequences of the disease and its treatments, such as pain killers,  treatment for anxiety, sleep disorders, etc.

Side effects of the treatments

Side effects related to surgery

In case of partial or total removal of the kidney, possible complications are those observed during any surgery, that is, hematomas, and risk of thromboembolism and infection.

In case of thrombosis, anticoagulants will be given, and antibiotics will be used in case of infection.

Partial nephrectomy can also be complicated by hemorrhage or urinary fistula, which means urine leaks around the operated kidney. To remedy this, a probe is used to connect the kidney and the bladder.

After an extended nephrectomy or, in rare cases, after a partial nephrectomy, mild or moderate kidney failure may occur if the kidney fails to return to normal function. In this case, the doctor will inform you of the precautions to be taken to prevent kidney failure from progressing.

Fatigue is common after surgery, especially due to anesthesia, anxiety, or loss of blood. If the fatigue persists, it is important to inform your doctor.

Finally, you can feel pain after the surgery, and it can last for a few weeks to a few months. Pain killers may be offered to you in this case. However, it is important to tell your doctor if you have persistent pain.

Side effects of medication

The side effects of medications used to treat renal cancer can occur more or less frequently. Each drug puts you at risk for side effects, however their frequency depends on the drug, its dose and on the patient themselves, as some people are at greater risk of side effects than others.

It is important to mention that side effects of a treatment are not related to its effectiveness. Having more or less severe side effects does not in any way indicate that the treatment is more or less effective.

Targeted therapy and immunotherapy drugs frequently cause digestive disorders, such as diarrhea, nausea and vomiting. Treatment may be prescribed in this case. Fatigue is also a common side effect.

Skin disorders may also develop, such as redness, dryness of the skin, blotches, itching, as well as the appearance of hand-foot syndrome (redness, swelling, dryness and blistering in the palms of the hands and soles of the feet) . To limit these disorders, it is important to regularly hydrate your skin with moisturizers, limit exposure of the hands and feet to heat, and avoid activities causing friction of the skin.

High blood pressure is frequently observed as the result of antiangiogenic drugs (see targeted therapies). It will require strict monitoring at each visit. It is also important to check the urine for protein (proteinuria), which is often associated with high blood pressure. A change of treatment may be considered in the event of a significant increase in proteinuria.

Targeted therapy and immunotherapy often have a certain impact on blood and bone marrow, such as decrease in the number of white blood cells (leukopenia), leading to a high risk of infections, decrease in the number of red blood cells, causing anemia, and finally, decrease in the number of platelets (thrombocytopenia), exposing the patient to a greater risk of hematomas and bleeding.

Regular blood tests are used to check the levels of white blood cells, red blood cells and platelets. However, it is important to consult your doctor in the event of fever or any other  disturbing symptoms (sore throat, chills, diarrhea, severe vomiting, etc.).

Certain medicines can also cause the appearance of lesions in the mouth (canker sores, redness, pain). In this case, it is important to maintain good oral and dental hygiene by brushing your teeth regularly and using a mouthwash.

It may also be necessary to avoid foods that cause the appearance of canker sores (nuts, Swiss cheese, pineapple). Tobacco and alcohol should also be avoided.

Finally, other side effects, more or less specific to the drug taken, may occur, such as shortness of breath, headaches, dizziness, nosebleeds, muscle and joint pain, as well as an allergic reaction to treatment.

Follow-up care

After the surgery, as well as during and after treatment for advanced cancer, medical follow-ups should be organised. This will make it possible to manage any adverse effects linked to surgery or treatment, to confirm remission through biological or radiological examinations, or to detect a possible recurrence of the disease.

This follow-up care will also allow the care team to monitor the patient's state of health, set up supportive treatments if necessary, facilitate social and professional reintegration, as well as ensure the patient's quality of life.

It will be discussed during a visit to the GP, with the participation of a specialized care team. The follow-up visits will be especially regular the first three years, the risk of recurrence being the highest during this period (80% of relapses are observed during the first three years), even if the risk is 1 to 2% after surgery. Then the visits will become more rare over time.

The follow-up care plan will be tailored to each patient, taking into account the stage of their disease at the time of diagnosis and the treatment received.

It will mainly be based on clinical, biological (blood tests to monitor renal function) and radiological (CT or MRI of the abdomen) examinations, as well as additional examinations if necessary.

In conclusion, kidney cancer accounts for about 3% of all cancers and affects twice as many men as women. The prevalence has been increasing in recent years, however death rates are declining and the recovery rate is relatively high. Treatment consists mainly of surgery for localized cancers, combined with medications for metastatic cancers. Follow-up care is then set up over the period of several years and consists of follow-up visits and various examinations (clinical, biological and radiological).

Sources :

Cancer du rein, Vidal

Le cancer du rein : points clés, Institut national du cancer

L'épidémiologie, info cancer

Qu’est-ce que le cancer du rein?, société canadienne du cancer

Chapitre 17 - Tumeurs du rein, association française d'urologie

Questions-Réponses sur le cancer du rein, association française d'urologie

Key statistics about Kidney cancer, cancer.org

Published Oct 31, 2021