What is kidney cancer?
Kidney cancer is a cancer that starts in the kidneys. It may also be referred to as renal cancer or renal carcinoma.
In 2015, it was estimated that a Canadian male’s lifetime probability of developing kidney cancer is 1 in 56. A Canadian female’s lifetime risk is 1 in 90.
Kidneys are about the size of a fist and there is one on either side of the spine near the bottom of the rib cage. Most people have two kidneys, although you can survive with only one functioning kidney. Kidneys are part of the urinary system, also referred to as the renal system.
Kidneys help to keep you healthy. Learn how you can protect yourself against kidney (renal) cancer.
Kidneys are essential organs that perform a number of important functions. Within each kidney there are:
- Tiny filters (called nephrons) that clean waste and water from the blood
- Tubes (called tubules) that
- reabsorb water, which helps to keep us hydrated and helps to regulate levels of important electrolytes, such as potassium and sodium (salt)
- send waste products to be excreted in the urine
- A funnel-like structure, called the renal pelvis, that directs urine through the ureter into the bladder, where it is stored until you urinate
The kidneys also produce a number of important hormones. For example, hormones produced by the kidneys help to regulate blood pressure, blood sugar and the production of red blood cells. The functioning of the kidneys can be impaired by factors such as disease, infections, inherited or congenital disorders, or benign or cancerous tumours.
Benign or non-cancerous changes in the cells that make up the kidneys can result in the formation of:
- cysts, which are round or oval fluid-filled pockets
- benign tumours
In some cases, tumours in the kidney may become cancerous. Malignant (cancerous) tumours may grow uncontrollably or interfere with the normal functioning of the kidneys.
The most common form of kidney cancer is called renal cell carcinoma. This cancer starts in the tubules and accounts for about 90% of all cases of kidney cancer. Less commonly, cancer can form in the renal pelvis (the top part of the ureter) or the collecting ducts (part of the tubule system).
Risk factors you can change or control
High blood pressure
Blood pressure is the force exerted on the walls of the blood vessels as blood is pumped through the body. Blood pressure changes throughout the day and according to what you are doing. But if your blood pressure is consistently higher than what is considered “normal” or “healthy,” it can damage the walls of the blood vessels. Having high blood pressure (hypertension) increases the risk of kidney cancer.
The risk of developing high blood pressure is higher if you have a family history of hypertension, are sedentary or overweight, eat a poor diet or drink too much alcohol. The risk of high blood pressure may also increase with age.
If you have been diagnosed with high blood pressure, it’s important to make changes to help lower your blood pressure and keep it in a healthy range. This can include making lifestyle changes, such as eating healthier or becoming more active. In some cases, your doctor or nurse practitioner may prescribe blood-pressure-lowering medications.
Being overweight or obese increases the risk of kidney cancer. The Body Mass Index (BMI) is a ratio of your height and weight that can be helpful in determining if you’re at a healthy weight. The BMI range between 18.5 and 24.9 kg/m2 is associated with a lower risk of many types of diseases, including cancer. As a result, people who fall into this range are described as being at a “normal” or “healthy” weight.
Studies suggest that every additional 5 units above 25.0 kg/m2 may increase the risk of developing kidney cancer by up to 30%. Losing even a modest amount of weight can help to reduce a person’s risk of kidney cancer.
The BMI is only one indicator of whether someone is at a healthy weight. The BMI may not be accurate for people who are very muscular, very short or very tall, pregnant or nursing, younger than age 18 or older than age 65. If you have concerns about your weight, talk with your doctor or nurse practitioner.
Risk factors you can't change or control
Studies suggest having a first-degree or “blood” relative with kidney cancer (i.e., a parent, brother, sister or child) nearly doubles your own risk of the disease.
What you can do to protect yourself
Manage your blood pressure
You can help to keep your blood pressure in a healthy range by:
- Eating a healthy diet that’s low in salt (sodium)
- Keeping and maintaining a healthy weight
- Regular physical activity
- Being smoke-free
- If you drink alcohol, limiting your consumption to no more than 1 drink per day for women or 2 per day for men
- Managing your stress level
If you’ve been diagnosed with high blood pressure and have been prescribed medication to lower your blood pressure, it is important to take it regularly, as instructed by your doctor or nurse practitioner. Never stop taking your medication without consulting with your doctor or nurse practitioner.
Maintain a healthy weight
Maintaining a healthy weight can help to reduce the risk of kidney cancer, as well as many other chronic diseases. The Body Mass Index (BMI) is calculated from a person’s height and weight. It is a rough indicator of whether a person is overweight. A BMI between 18.5 to 24.9 kg/m2 is associated with a lower risk of many diseases and so is considered a “healthy” range for most people. A BMI of 25.0 kg/m2 or more is associated with a higher risk of many diseases – including kidney cancer.
If you’re not at a healthy weight, losing even a modest amount of weight can help to reduce the risk to your health. Small changes in diet and physical activity may be enough to help you become healthier.
Curious about the body Mass Index (BMI)? To find out more, visit Dietitians of Canada.
Most people are aware that smoking increases the risk of lung cancer. But many aren’t aware that smoking increases the risk of many other cancers, including kidney cancer. There is no safe level of smoking.
Some people find that it takes several attempts to quit smoking. So if you’ve tried to quit in the past and have relapsed, don’t give up. Each time you try to quit, you’re getting closer to your goal of being permanently smoke-free.
Access tools to help you become tobacco-free at Smokers' Helpline, including:
- An online community
- Support from a Quit Coach by phone or text
- Self-directed and personalized information to help you reach your goals