Kidney cancer is one of the top 10 most common cancers in the U.S. The American Cancer Society estimates that more than 81,000 Americans are diagnosed with kidney cancer each year.

If you or a loved one has recently been diagnosed with kidney cancer, it’s vital to learn the basics about this disease, from symptoms and treatment plans to prognosis (outlook). In this article, we’ll review important facts you should know about kidney cancer so you can have better conversations with your doctor.

1. In Kidney Cancer, a Tumor Grows in the Kidneys

Cancer is a condition in which cells begin to grow out of control. Eventually, the abnormal cell growth can turn into a mass of cells, called a tumor. Kidney cancer develops when kidney cells begin to grow out of control.

You have two kidneys, which are found right below your rib cage, with one on each side of your backbone. Each kidney is shaped like a bean and about the size of your closed fist. Your kidneys have many important jobs to keep your body functioning, including:

• Cleaning waste products from the blood
• Balancing fluids and electrolytes (salts)
• Making hormones that help maintain your blood pressure and red blood cells

The excess fluid, electrolytes, and waste products that the kidneys filter out of the blood make up the contents of your urine.

Not All Kidney Tumors Are Considered Cancer

Not all kidney masses are cancerous. About 1 in 4 kidney masses are considered benign (noncancerous). A kidney tumor is considered cancerous if the cells have genetic changes that cause the cells to grow out of control and metastasize (spread to nearby tissues). That said, even if a kidney mass isn’t considered cancerous, it can still grow larger and cause health problems.

2. Renal Cell Carcinoma Is the Most Common Type

There are several different types of kidney cancer, but the most common type is renal cell carcinoma (RCC). Between 80 percent and 85 percent of people with kidney cancer are diagnosed with RCC. In RCC, cancer develops in the lining of the renal tubules (small tubes that help the kidneys filter the blood).

Researchers classify RCC into several different subtypes based on how cancer cells look under a microscope. About 70 percent of RCC cases are clear cell RCC. These cancer cells typically look clear or pale under the microscope. Other subtypes of RCC that aren’t clear cell are known as non-clear cell RCC. There are several types of non-clear cell RCC, including papillary RCC and chromophobe RCC.

Less Common Types of Kidney Cancer

Kidney cancer can develop in parts of the kidney other than the renal tubules. If this occurs, it can cause different, less common types of kidney cancer.

Transitional cell carcinoma (TCC, also called urothelial carcinoma) happens when cancer grows in the renal pelvis. The renal pelvis is where the kidneys meet the ureters (the tubes that take urine to the bladder). This type of cancer often looks like bladder cancer under the microscope.

Renal sarcoma is a type of kidney cancer that develops in the connective tissue or blood vessels of the kidneys. Renal sarcomas are rare, with only about 1 percent of people with kidney cancer diagnosed with renal sarcoma.

Wilms tumor (also known as nephroblastoma) is a type of kidney cancer that occurs in children. About 90 percent of kidney cancers diagnosed in children are Wilms tumors.

3. Older Age and Other Factors Increase Risk for Kidney Cancer

The risk of kidney cancer increases with age. Most people are diagnosed with kidney cancer between the ages of 65 and 74.

Researchers don’t know why some kidney cells become cancerous. However, according to the National Kidney Foundation, there are several risk factors associated with a higher risk of kidney cancer, including:

• Male sex
• Having a family history of kidney cancer
• Having American Indian or Alaska Native heritage
• Smoking
• Having certain medical conditions, including obesity and high blood pressure
• Having advanced kidney disease, especially disease requiring dialysis treatment
• Having a genetic disease, such as von Hippel-Lindau disease or Birt-Hogg-Dube syndrome
• Long-term use of pain medications, including acetaminophen (Tylenol) and possibly aspirin
• Exposure to certain chemicals, including cadmium

4. You May Not Have Symptoms in Early Stages

Kidney cancer usually doesn’t cause symptoms until it advances and the tumor grows larger. Possible symptoms of kidney cancer may include:

• Blood in the urine
• Lower back pain
• Lump in the side or lower back
• Unexplained weight loss
• Night sweats
• Fever
• Extreme tiredness
• Loss of appetite
• Paleness

The lack of early symptoms means that kidney cancer is often diagnosed after it’s begun to spread. About 25 percent of those diagnosed with kidney cancer have locally advanced or metastatic disease, or cancer that has spread to nearby tissues or distant parts of the body.

5. Half of Kidney Cancers Are Found by Chance

More than half of kidney masses are found by chance, instead of testing in response to kidney cancer symptoms. For some people, kidney cancer is found when their doctor orders an imaging test for an unrelated condition.

If your doctor suspects you may have kidney cancer from imaging tests or because of your symptoms, you’ll need additional testing. Your doctor will refer you to a urologist for kidney cancer diagnostic testing.

Many people can be diagnosed with kidney cancer with an imaging test, such as a CT scan, an MRI scan, or an ultrasound test. In some cases, the image of your kidneys created by a CT scan or MRI scan is enough to make a diagnosis.

However, some people may need a kidney biopsy to confirm the diagnosis. In a kidney biopsy, your healthcare provider will remove a small sample of kidney tissue to check for cancer cells.

Other ways to diagnose kidney cancer may include:

• Medical history — To check for risk factors and symptoms of kidney cancer and ask about family history of cancer
• Physical exam — To look for signs of kidney cancer, such as a lump in your back or abdomen
• Blood tests — To look for signs of kidney cancer in your blood, such as anemia (low red blood cell count) or high calcium levels
• Urine tests — To check the levels of proteins and chemicals in your urine and to look for cancer cells

6. Surgery Is the Most Common Treatment for Kidney Cancer

Your cancer care team will recommend treatment options for you based on the stage, grade, and type of kidney cancer you have. Surgery to remove all or part of the kidneys is the most common kidney cancer treatment.

The type of surgery you have depends on the location and stage of the kidney tumor. In a simple nephrectomy, a surgeon will remove the entire kidney. If only the part of the kidney with the tumor is removed, it’s called a partial nephrectomy. In some cases, the surgeon may have to remove the kidney with some of the surrounding tissue or lymph nodes. This is called radical nephrectomy.

Ablation (local treatments to destroy the kidney tumor) can be used in some people with medical conditions that prevent them from having surgery. Ablation treatments use extreme heat or cold to destroy cancer cells. Examples of ablation treatments for kidney cancer include cryoablation or radiofrequency ablation. Radiation therapy is another treatment option for people who aren’t healthy enough to have surgery.

People who have advanced kidney cancer or a high risk of recurrence (cancer coming back after treatment) may also receive targeted therapy or immunotherapy treatments. Chemotherapy treatments used in other types of cancer aren’t usually effective for most types of kidney cancer.

Some people with small kidney tumors may not need treatment right away. In this case, active surveillance may be an option. In active surveillance, you’ll have regular imaging tests and blood tests to check for signs that the cancer is growing or spreading.

7. Early Detection of Kidney Cancer Leads to Better Outcomes

When kidney cancer is found and treated before it’s spread outside of the kidney (localized stage), 93 percent of people are alive at least five years after diagnosis. This measurement is known as the five-year relative survival rate.

If kidney cancer is found after it has begun to spread to tissues around the kidney (regional stage), the five-year relative survival rate is about 75 percent. The five-year survival rate for kidney cancer that’s spread to distant parts of the body is 18 percent.

The survival rates for kidney cancer highlight that people who are diagnosed with kidney cancer in the early stages have a better prognosis. Other factors that may affect your prognosis include your age, overall health, and how you respond to treatment. Your cancer care team can give you more information about your prognosis based on your individual factors.

Find Your Team

On MyKidneyCancerTeam, the social network for people living with kidney cancer and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with kidney cancer.

Have you or a loved one been diagnosed with kidney cancer? Share your experience in the comments below, or start a conversation by posting on your Activities page.