Kidney cancer is the abnormal growth of cells in the kidneys. It accounts for approximately 2% of all cancers worldwide. The occurrence and mortality rates of kidney cancers are rising by 2-3% per decade. Kidney cancer is the ninth most common cancer in men and the 14th most commonly occurring cancer in women. Most people with kidney cancer are elderly people and are usually diagnosed between the age of 65 and 74 years.
What is Kidney Cancer?
The kidneys are a pair of fist-sized, bean-shaped organs positioned on either side of spine, below the rib cage and behind the abdomen. It plays a crucial role in filtering the blood and removing excess water, salt, and waste products from the body.
Kidney cancer begins when cells in the kidneys grow uncontrollably and form a tumor. Based on the type of cells where the cancer begins, kidney cancer is further divided into the following types:
- Renal cell carcinoma (RCC): It is the most common type of kidney cancer that originates in the lining of small tubules inside the kidney. RCC accounts for 90% of kidney cancer.
- Transitional cell carcinoma or Urothelial carcinoma: It accounts for about 7% of kidney cancers. It does not originate in the kidney but begins in the lining of the renal pelvis (the point where ureters meet the kidneys).
- Wilms’ tumor: It develops during the childhood and accounts for 1% of kidney cancers.
- Renal sarcoma: It is a rare type of kidney cancer that originates in the soft tissues of kidney.
Signs and symptoms
Kidney cancers are asymptomatic during its early stages. However, in advanced stages, the possible signs and symptoms of kidney cancer include:
- Blood in the urine
- Back pain on one side
- A lump in abdomen or lower back
- Loss of appetite
- Unexplained weight loss
If cancer spreads beyond the kidney, the person may have symptoms, such as shortness of breath, coughing-up blood, bone pain, or any other specific organ related symptoms.
Causes and Risk factors
The exact cause of kidney cancer is not known, but researchers believe that kidney cancer begins when cells in one or both kidneys undergo mutation and divide in an uncontrollable rate forming a mass called tumor.
There are several factors that may increase the risk of kidney cancer. These include the following factors:
- High blood pressure
- Male gender
- Specific inherited syndromes, such as Von-Hippel-Lindau disease
- Family history of kidney cancer
- Certain medications
- Long-term dialysis
- Long-term exposure to a chemical called trichloroethylene
Kidney cancer is often diagnosed accidentally during imaging tests for another reason. If kidney cancer is suspected, then the signs and symptoms, medical history, and family history of the patient is reviewed.
In addition to a physical examination, blood tests and urinalysis are also performed. These tests may suggest the presence of kidney cancer, but they cannot be used to make a definite diagnosis.
The following tests are recommended to diagnose kidney cancer:
Biopsy: It involves collecting a small sample of tumor and viewing it under a microscope to determine if it is cancerous or non-cancerous. The procedure is guided by CT or MRI scan. Techniques used to collect the kidney tissue samples are fine-needle aspiration and needle core biopsy.
Imaging tests: Tests such as computerized tomography (CT), magnetic resonance imaging (MRI) scan, ultrasound, chest X-ray, bone scan and angiography are recommended to visualize a kidney tumor and to check whether the tumor has spread to other body parts like bone, blood vessels etc.
Stages of kidney cancer:
The commonly used staging system for kidney cancer is the TNM system. It provides detailed information about:
- Tumour (T): Whether the primary tumour has grown through the kidney wall
- Node (N): Whether the cancer has spread to the surrounding lymph nodes
- Metastasis (M): Whether the cancer has spread to distant parts of the body
Based on the TNM system, kidney cancer can be of the following stages:
- Stage I: Cancers are confined to the kidney and is 7 cm or smaller cm in diameter.
- Stage II: Cancers are confined to the kidney, but the tumor is larger than 7 cm in diameter.
- Stage III: The cancer has spread into major veins or perinephric tissues and may or may not have spread to lymph nodes; OR
Cancer cells may be outside the kidney, but has not spread beyond Gerota’s fascia (tissue that encapsulates the kidneys). The cancer has spread to lymph nodes but not to the distant organs.
- Stage IV: Cancer has spread to distant parts of the body like lung, liver, or bones.
The treatment is decided depending on the type and stage of kidney cancer. Based on the benefits, possible risks, and side effects, the following treatment modalities may be recommended:
Surgery: Surgery is the mainstay of treatment for kidney cancer. It can be performed as an open procedure, or laparoscopically or with robotic assistance. Surgical procedures used to treat kidney cancer are:
- Nephrectomy: The procedure involves surgical removal of the whole kidney. It is recommended for stage I kidney cancer.
- Partial nephrectomy: In this procedure, only the part of the kidney that contains cancer is removed, leaving the healthy part of kidney behind.
- Radical nephrectomy: In this procedure, the whole affected kidney along with the attached adrenal gland, nearby lymph nodes, and the surrounding fatty tissues are removed. It is often recommended for stage II and stage III kidney cancer.
Surgical alternatives (Local therapies): Surgery is not recommended for elderly patients or people with multiple medical conditions. In such cases, nonsurgical treatments are considered safe and appropriate. The procedures include:
- Cryotherapy (cryoablation): This therapy uses extreme cold temperature to destroy the tumor. During the procedure, a specialized needle is inserted into the tumor through a small incision using ultrasound or other image guidance. Cold gas is passed through the needle to freeze the cancer cells.
- Radiofrequency ablation (RFA): This uses high-energy radio waves to heat the tumor. During the procedure, thin, needle-like probe is placed near the tumor using ultrasound or other image guidance. An electric current is passed through the tip of the probe to destroy the cancer cells.
Targeted therapy: This involves the use of drugs that targets specific genes, proteins, or the tissue that contributes to cancer growth and survival. In kidney cancer, targeted therapy is used:
- For treating advanced cancer
- After the surgery to prevent the recurrence
Immunotherapy: This is also known as biologic therapy. It involves the use of specific drugs that work by stimulating body’s own immune systems to fight cancer. It is often recommended as an adjuvant treatment to prevent the recurrence of cancer.
Chemotherapy: It involves the use of potent drugs that interfere with the cell division and destroy cancer cells. These anti-cancer drugs are given through a vein (IV) or taken orally. Chemotherapy is not a standard treatment option for kidney cancer as most of the kidney cancer cells are resistant to chemo.
Radiation therapy: It involves the use of high energy beams like X-rays to destroy tumors. It is not an effective treatment for kidney cancer. Radiation therapy is often recommended when a patient cannot undergo surgery. It is used as:
- A palliative therapy to ease cancer symptoms during the advanced stage of cancer.
- An adjuvant therapy after the surgery to destroy the remaining cancer cells.
There is no proven way to completely prevent kidney cancer. Managing some risk factors may help in lowering its risk. Preventive measures include:
- Smoking cessation
- Maintaining a healthy body weight
- Avoiding exposure to harmful carcinogens like trichloroethylene
- Controlling high blood pressure
Kidney cancer tends to be “silent,” as it does not show any symptoms until it has spread outside the kidneys. Though the survival rate depends on the stage of cancer at the time of diagnosis, the average five-year survival rate in kidney cancer patients is 75%. Early stage detection helps in offering the best treatment and positive long-term outcome.
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