Renal cancer, also known as kidney cancer, begins when cells in the kidney tissue start to grow and divide without control, eventually forming a mass called a tumor. This disease affects thousands of people each year and is most commonly discovered in people between the ages of 60 and 70, with men being diagnosed about twice as often as women.
Understanding How Common Renal Cancer Is
Kidney cancer represents approximately 3.7 percent of all cancers diagnosed in the United States. Each year, more than 62,000 Americans receive a diagnosis of kidney cancer, and the disease causes about 14,000 deaths annually. According to estimates from medical organizations, more than 81,000 new cases of kidney cancer will be diagnosed in the United States in 2023. The risk of developing this cancer increases with age, making it particularly important for older adults to be aware of the warning signs.[2][10]
The disease affects different populations at varying rates. Men are twice as likely as women to develop kidney cancer, and the condition is more common in Native American and Black populations compared to other ethnic groups. The average age of diagnosis is 64 years old, with most cases occurring in people between 65 and 74 years of age. This pattern suggests that kidney cancer develops over many years, likely as a result of accumulated cellular changes and exposure to various risk factors throughout a person’s lifetime.[1][2]
What Causes Renal Cancer
The exact causes of kidney cancer remain unknown to medical researchers. What scientists do understand is that the disease develops when something triggers changes in the cells of the kidney, causing them to behave irregularly. These cellular changes affect the DNA (the genetic material inside cells), which controls how cells grow and divide. When DNA changes occur in kidney cells, they may begin to grow in abnormal ways, forming tumors. This is the fundamental process of how cancer develops in the kidney and other organs.[1][9]
While the underlying cause is not fully understood, researchers have identified specific genetic changes associated with different types of kidney cancer. Studies have found that the VHL gene plays a role in the development of both sporadic and familial types of clear cell renal cell carcinoma (a specific type of kidney cancer where the cells appear clear under a microscope). In some cases, mutation in the MET gene is a feature of the familial type of papillary renal cell carcinoma (another type where the tumor has finger-like projections). These genetic discoveries have helped scientists develop new treatments that target these specific molecular changes.[5]
About 4 percent of renal cell cancers result from rare hereditary conditions. One of the most well-known is Von Hippel-Lindau syndrome, which is associated with the development of cysts and tumors in various organs, including multiple bilateral tumor nodules of clear cell renal cell carcinoma. People with this syndrome have a much higher risk of developing kidney cancer compared to the general population. There are ten familial syndromes in total that confer greater risk of developing renal cell carcinoma, and people with these conditions often require regular monitoring for early detection of tumors.[5][9]
Risk Factors That Increase Your Chances
Smoking is one of the strongest risk factors for developing kidney cancer. People who smoke tobacco are at significantly greater risk compared to non-smokers, and importantly, the longer a person smokes, the higher their risk becomes. This elevated risk applies not just to cigarette smokers but also to those who smoke pipes and cigars. The good news is that quitting smoking can reduce this risk over time, making it one of the most important preventive actions a person can take.[1][2]
Obesity is another major risk factor for kidney cancer, particularly in women. In general, the more overweight a person is, the higher their risk of developing the disease. This connection may be related to hormonal changes that occur with excess body weight, as well as chronic inflammation that obesity can cause in the body. Maintaining a healthy weight through balanced eating and regular physical activity can help reduce this risk.[2][4]
High blood pressure, also called hypertension, has been linked to an increased risk of kidney cancer. It remains unclear whether the increased risk comes from the high blood pressure itself or from the medicines used to treat it, but the association is well-documented. People with high blood pressure should work with their healthcare providers to keep their blood pressure under control, which benefits overall health in many ways beyond just cancer prevention.[2][9]
Long-term misuse of certain pain medicines, including some over-the-counter medications, can increase the risk of renal cell cancer. Additionally, people who have been on long-term dialysis (a treatment that filters the blood when kidneys fail) or have chronic kidney failure face higher risks. Women who have been treated with radiation therapy for certain cancers may also have an elevated risk of developing kidney cancer later in life.[2][9]
Having a family history of kidney cancer increases a person’s risk of developing the disease themselves. This suggests that genetic factors play a role in some cases, even when a specific hereditary syndrome has not been identified. Occupational exposure to certain chemicals represents another important risk factor. Trichloroethylene, a chemical used to remove grease from metal, has been specifically associated with the development of renal cell carcinoma and increased mortality from the disease. Workers who are mechanics, dry cleaners, oil processors, polyvinyl chloride manufacturers, and low-nicotine tobacco producers may encounter this chemical in their workplaces.[2][4][5]
Signs and Symptoms to Watch For
One of the challenging aspects of kidney cancer is that it may not produce any noticeable symptoms in its early stages. This means that small tumors can grow without causing any discomfort or visible signs that something is wrong. As the tumor grows larger, symptoms may begin to appear, but by this time the cancer may have already started to spread. For this reason, kidney cancer is often not diagnosed until it has begun to advance, which is why more than half of all patients with kidney cancer are asymptomatic when their cancer is discovered.[1][2]
The most common symptom of kidney cancer is blood in the urine, a condition called hematuria. This may make the urine appear pink, red, or cola-colored. Sometimes the blood is not visible to the naked eye and can only be detected through laboratory tests. Blood in the urine serves as an important warning sign that necessitates further evaluation and imaging by a healthcare provider.[2][19]
People with kidney cancer may notice a lump or mass in their kidney area or abdomen. This mass might be felt during a physical examination by a doctor, or occasionally, a person might notice it themselves. Pain in the flank area (the side of the body between the ribs and hip) is another possible symptom. This pain is different from muscle strain and does not go away with rest or typical pain management strategies.[2]
General symptoms can include persistent tiredness, a loss of appetite, and weight loss for no reason that a person can identify. Some people experience a general sense of not feeling well without being able to pinpoint a specific problem. Less common symptoms include a low-grade fever that comes and goes, high blood pressure, anemia (a low red blood cell count), and high calcium levels in the blood. Bone pain may occur if the cancer has spread to the bones. Because these symptoms can be caused by many other conditions, it is essential to see a healthcare provider for proper evaluation if any of these signs appear.[1][2]
How to Reduce Your Risk
Screening for renal cell carcinoma is not recommended for the general population, except for people with known hereditary syndromes associated with the development of kidney cancer. These individuals may benefit from regular monitoring. For most people, prevention focuses on reducing known risk factors through lifestyle modifications.[19]
The most important preventive measures include keeping a healthy weight, not smoking (or quitting if you do smoke), and managing high blood pressure. These three actions address the major modifiable risk factors for kidney cancer. Maintaining a healthy weight involves eating a balanced diet and staying physically active. Regular exercise not only helps with weight management but also contributes to overall health and may reduce cancer risk through multiple mechanisms.[4]
Evidence from research studies suggests that certain dietary habits may help reduce the risk of developing renal cell carcinoma. Consuming fatty fish appears to lower risk, as does eating three or more servings of fruits and vegetables daily. Moderate alcohol consumption (about one alcoholic beverage daily) has also been associated with reduced risk in some studies. However, it is important to note that while these dietary patterns show promise, they should be part of an overall healthy lifestyle rather than viewed as guaranteed prevention strategies.[19]
If you work with certain chemicals, especially trichloroethylene, it is very important to be careful and follow all safety protocols. This includes wearing appropriate protective equipment, working in well-ventilated areas, and following your employer’s safety guidelines. Workers in industries that use these chemicals should be particularly vigilant about protection measures to minimize exposure.[4][5]
How the Disease Affects the Body
To understand how renal cancer affects the body, it helps to know what the kidneys normally do. The body has two kidneys, one on each side of the backbone, located above the waist behind the liver and stomach. Each kidney is about the size of a fist and has a bean-like shape. The kidneys perform several vital functions: they filter excess water, salt, and waste products from the blood and turn these substances into urine. They also play a role in controlling blood pressure and stimulating the bone marrow to make red blood cells.[1][9]
Kidneys are made up of cellular tissue, including tiny tubules (very small tubes) that filter and clean the blood. Renal cell cancer forms in the lining of these tubules inside the kidney. When cells in these tubules begin to behave irregularly due to changes in their DNA, they grow in abnormal ways and form tumors. The most common type of kidney cancer in adults is renal cell carcinoma, which accounts for about 85 to 90 percent of all kidney cancers. Within this category, clear cell renal cell carcinoma is the most frequent subtype, making up about 70 to 80 percent of renal cell cancers.[2][8]
As a tumor grows in the kidney, it can interfere with the kidney’s normal functions. The tumor may block the flow of urine or damage the filtering structures within the kidney. If the cancer grows large enough or spreads beyond the kidney, it can affect nearby organs and tissues. When cancer cells break away from the original tumor and travel through the bloodstream or lymphatic system to other parts of the body, this is called metastasis. A cancerous or malignant tumor has this ability to spread to other tissues and vital organs, which distinguishes it from benign (non-cancerous) tumors that stay in one place.[2]
The kidneys have a remarkable ability to maintain function even when partially damaged. Most people can live normally and healthily with one working kidney or with only part of a kidney, because the remaining kidney tissue can still effectively filter waste and extra water from the blood. However, when cancer affects both kidneys or when the remaining kidney tissue is not completely healthy, more serious complications can develop, including kidney failure that may require dialysis.[23]
Different types of renal cell cancer affect the body in slightly different ways. Papillary renal cell carcinoma (making up 15 to 20 percent of cases) develops finger-like projections. Chromophobe renal cell carcinoma (about 5 percent of cases) arises from a different type of cell in the kidney. There are also rare types including cancer of the collecting duct and renal medullary cancer. Each type has distinct characteristics under the microscope and may respond differently to treatments. About 5 percent of renal cell cancers have sarcomatoid features, meaning that some cancer cells look like sarcoma cells under a microscope. This type tends to grow more quickly than other types and is more likely to be diagnosed at an advanced stage.[5][8]
