Definition and Overview
The kidneys are a pair of organs that filter the blood to remove wastes and extra fluid. Located in the back of the abdomen, they also help regulate the balance of electrolytes and produce substances that are necessary for the formation of red blood cells. The kidneys have a filtering system that consists of tubules or small canals.
Clear cell carcinoma of the kidney is the most common type of kidney cancer, accounting for more than 90% of all neoplasm arising from the kidneys. It is also responsible for approximately 3% of all adult malignancies. Also called renal cell carcinoma (RCC), it develops when malignant cells form in the kidneys’ tubules, which transport waste molecules from the blood to the urine. Just like mesothelioma (cancer of the lining of the lungs), RCC is also an aggressive type of cancer and often spreads to the lungs and surrounding organs. However, recent advances in the management of this condition have successfully extended the lives of patients even those with advanced cases.
Causes of the Condition
Just like other types of cancer, the causes of clear cell carcinoma of the kidney remain unknown. What is known, however, is that it occurs most often in men aged between 50 and 70 years old. Risk factors that can increase one’s chances of developing renal cell cancer include:
Polycystic kidney disease, a genetic or inherited disorder in which clusters of benign cysts develop in the kidneys. Although the growths are non-cancerous, they can cause complications, including high blood pressure and even kidney failure.
Von Hippel-Lindau disease, another genetic condition that is associated with tumours. But unlike polycystic kidney disease, these tumours grow in multiple organs, including the brain and the eyes.
A family history of the disease
High blood pressure
Other risk factors include exposure to asbestos, chronic hepatitis C infection, acquired renal cystic disease, end-stage renal failure, and tuberous sclerosis.
Kidney cancer symptoms include abdominal pain, haematuria (blood in urine), and the presence of a palpable mass. Other symptoms that may seem unrelated to the condition include hypercalcemia, leukemoid reactions, wasting syndrome, and Cushing’s syndrome. Patients suffering from these symptoms rarely consider renal cancer until they are diagnosed through radiographic investigation done for other reasons. Other non-specific symptoms of kidney cancer include vision problems, pale skin, excessive hair growth in females, flank pain, loss of appetite, and weight loss.
Who to See and Types of Treatments Available
Patients exhibiting symptoms mentioned above must undergo various diagnostic procedures to help doctors make an accurate diagnosis. Tests usually begin with a physical exam and review of the patient’s medical history. A blood chemistry study, in which amounts of certain substances released by the body’s tissues and organs are measured, is also usually performed.
Such tests are typically followed by imaging tests, which include ultrasound, a CAT (computerised axial tomography) scan, and magnetic resonance imaging (MRI) to create images of the internal organs. If an abnormal growth is found, a biopsy will be performed wherein a thin needle is inserted into the tumour to obtain a small amount of tissue sample. The sample is then tested to determine whether the growth is benign (non-cancerous) or malignant (cancerous).
If tests suggest that the tumour is malignant and may have already spread to other organs, a liver function test is performed to measure the amount of enzymes released by the liver. An abnormal amount of an enzyme can be a sign that cancer has already spread to the liver.
To identify the best course of treatment, doctors determine the stage of cancer based on its size and location. Doctors also determine if there’s lymph node involvement and if cancer has spread to distant areas of the body (distant metastasis).
Stages I and II kidney cancer mean that the cancer is localised to the kidneys. It is categorised as stage II when the tumour has grown to at least 7 centimetres. Stage III kidney cancer means that it has already spread to nearby lymph nodes. Stage 4, on the other hand, has spread to distant organs, including the brain, bones, liver, and lungs.
Treatment options include surgery, chemotherapy, and radiation therapy. Surgical procedures performed for the treatment of renal cancer include partial nephrectomy (removal of a kidney tumour), simple nephrectomy (removal of the diseased kidney), and radical nephrectomy (removal of the kidney, nearby lymph nodes, adrenal gland, and surrounding tissues). Patients whose both kidneys are removed will require life-long dialysis and later on, a kidney transplant. Surgical procedures mentioned above are typically followed by chemotherapy and radiation therapy. Both aim to kill cancer cells that are left by surgery.
Patients can also take advantage of biologic or immunotherapy in which their body’s natural defenses against illnesses are boosted using synthetic substances developed in a laboratory. Another treatment option is called targeted therapy, which attacks cancer cells without harming healthy ones.
All treatment options, along with their advantages and disadvantages, are thoroughly discussed by the patient’s medical team before any treatment is initiated. Doctors also ensure that the benefits of treatment outweigh potential risks.
The prognosis depends on the stage of cancer and how soon the patient received treatment. Patients with stage I renal carcinoma are more likely to make a full recovery. However, the survival rate is much lower for those whose condition was caught late and has already spread to distant organs.
According to the National Cancer Institute, the 5-year survival rate for clear cell carcinoma of the kidney is up to 70%. However, it is important to note that even if cancer has been treated, patients may still suffer from poor kidney function. For this reason, long-term dialysis is typically prescribed along with drug therapy. In the case of kidney failure, a kidney transplant is required for patients to survive.
National Cancer Institute: PDQ renal cell cancer treatment. Bethesda, MD: National Cancer Institute. www.cancer.gov/types/kidney/hp/kidney-treatment-pdq.
National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology: kidney cancer. Version 2. 2016. www.nccn.org/professionals/physician_gls/pdf/kidney.pdf.