Overview
Kidney cancer begins in the kidneys, two bean-shaped organs on either side of your spine and just above your hips, behind your abdominal organs. Your kidneys remove excess waste and water from your blood to create urine, create hormones like adrenaline, and regulate the presence of acid, salt, and minerals in your body, such as calcium and potassium.
Sometimes, your kidneys develop masses either inside them or on the surface. Some of these masses are harmless. Usually, one in four masses in our kidneys is benign. Smaller masses are generally benign, but some small masses can grow larger and become tumors over time.
The American Cancer Society estimates that around 76,000 people will be diagnosed with kidney cancer in 2021 in the United States, and almost 14,000 will die from it. It is one of the ten most common cancers in the country. The incidence of kidney cancer has been increasing steadily since the 1990s, but the death rates have remained relatively stable, making some doctors believe that this increase is due to the increased use of imaging systems like CT scans, which make spotting the cancer easier.
There are three main types of tumors that can form in your kidneys:
Renal Cell Carcinoma (RCC): Also called renal cell cancer, this is the most common form of kidney cancer in adults. With RCC, the tumors form in the area of the kidney where the filtering work is done. RCC begins in the tubules of the kidneys, the tiny vessels that filter the blood and spreads outward. There are several different subtypes of RCC.
Benign tumors: One in four tumors in your kidneys are benign and will not become cancerous.
Wilm’s tumors: Wilm’s tumors are the most common form of kidney cancer in children. They can grow much larger than the kidney in which they started.
Symptoms
Symptoms of kidney cancer vary widely but are not usually severe until the cancer grows or metastasizes (spreads to other organs). Symptoms include the following:
- Blood in the urine
- Pain in the side or back that doesn’t go away
- Loss of appetite
- Lump in the side or back
- Weight loss
- Fever
- Fatigue
- Anemia
- Vision problems
Causes
The exact cause of kidney cancer is unknown, but the cancer starts like other types of cancer: mutations in the DNA of your kidney cells that cause new cells to grow rapidly and spread. These mutations are either inherited or acquired. There are several other risk factors that are discussed in detail below.
Risk Factors
Although we don’t know the exact cause of kidney cancer, we do know that certain behaviors and genetic traits increase the risk of having kidney cancer at some point in life. The risk factors include:
- Smoking: Smoking cigarettes puts many different carcinogenic chemicals in the bloodstream, and when the kidneys filter the blood, these chemicals can build up in the kidneys and cause cancer later in life.
- Obesity: People who are obese have almost twice the risk of kidney disease and cancer. Obesity changes the hormones that our kidneys create, such as insulin, and a diet high in fats and protein can affect our kidney function.
- A family history of kidney cancer: If any close family member has contracted kidney cancer, especially a sibling, you’re at a much higher risk for developing it yourself.
- Gender: Men are twice as likely to develop kidney cancer as women.
- Age: Kidney cancer is relatively uncommon in people under 45. The average age at diagnosis is 64.
- Dialysis: Being on dialysis for another type of kidney disease greatly increases the risk of kidney cancer.
- High blood pressure: Having high blood pressure increases kidney cancer risk, but some doctors believe this may be due to the medications used to treat high blood pressure and not the condition itself.
- Exposure to certain chemicals: Exposure to chemicals like asbestos, cadmium, some herbicides, or organic solvents can increase the risk of kidney cancer.
- Long-term use of medication: Using some over-the-counter pain medication like Tylenol or ibuprofen for a long period of time can increase the risk of kidney cancer. One study found that people who regularly took pain medication over a ten-year period showed a 300% increase in instances of kidney cancer.
- Lymphoma: People with lymphoma carry a higher risk of kidney cancer.
- Being black: Doctors aren’t sure why, but black people have a higher risk of kidney cancer than white people.
Survival Rates
According to the American Cancer Society, the five-year relative survival rate for kidney cancer after accounting for the various types is around 75%. This number is an average and changes depending on the extent of the cancer discovered.
The ACS reaches this number by looking at statistics from the SEER database maintained by the National Cancer Institute. SEER stands for Surveillance, Epidemiology, and End Results. The database divides survival rates into three categories based on the type of cancer:
- Localized: No sign that cancer has spread outside the kidney. Survival rates for this type are around 93%.
- Regional: Cancer has spread to nearby structures and lymph nodes. Survival rates for this type are around 70%.
- Distant: Cancer has spread to organs, bones, and brain. Survival rates for this type are around 13%.
Treatment for kidney cancer can be delivered through medication, surgery, or other more aggressive treatments like radiation therapy. In most cases, surgery will be the first option. Here are some of the more common treatments:
- Partial nephrectomy: Removing the part of the kidney that is cancerous.
- Simple nephrectomy: Removing the entire affected kidney. People can live a normal, healthy life with one kidney.
- Radical nephrectomy: Removing the kidney and surrounding tissue, like the adrenal gland and lymph nodes.
- Radiofrequency ablation: Using targeted microwave radiation to ‘cook’ the tumor.
- Cryotherapy: Using extreme cold to freeze the tumor.