What Is Kidney Cancer? Symptoms, Causes, Diagnosis, Treatment, and Prevention
Kidney cancer is a type of cancer that starts in the kidneys — two bean-shaped organs located just below the rib cage, one on each side of the spine.
In a healthy person, the main job of the kidneys is to filter blood by removing waste and extra water and salt to make urine. The kidneys also make specific hormones that help the body control blood pressure and produce red blood cells.
Kidney cancer happens when healthy cells in a kidney grow out of control and form a tumor.
As with most cancers, the earlier kidney cancer is diagnosed and treated, the better the outlook. Researchers are currently looking at innovative ways to detect and target kidney cancer more effectively.
“There have been significant advances in kidney cancer over the last decade and the field is rapidly changing,” says Chung-Han Lee, MD, PhD, a medical oncologist at Memorial Sloan Kettering Cancer Center in New York City.
Types of Kidney Cancer
There are many different types of kidney cancer, each of which may be managed and treated differently.
Renal cell carcinoma About 90 percent of all kidney cancers are renal cell carcinomas.
With renal cell carcinoma, cancer cells grow in the lining of the kidney tubules and form into a tumor. (The tiny tubules play an essential role in filtering waste and returning needed nutrients to the bloodstream.)
This type of cancer usually develops as a single mass, although sometimes one kidney will contain multiple tumors. In other cases, tumors might affect both kidneys at the same time.
There are several subtypes of renal cell carcinoma, which are divided into two main categories: clear cell renal carcinomas and non-clear cell renal carcinomas.
Clear cell renal cell carcinoma is the most common type of renal cell carcinoma, making up about 70 percent of cases. With clear cell renal cell carcinoma, cancer cells appear very pale or clear, which explains its name.
Non-clear cell renal cell carcinomas include the following:
Papillary renal cell carcinomas These cancer cells create finger-like projections, known as papillae, in the tumor. This is the second most common subtype of renal cell carcinoma, making up about 10 percent of cases.
Chromophobe renal cell carcinomas Cancer cells in this type appear pale like clear cells but are much larger and have other distinct features. This subtype accounts for about 5 percent of renal cell carcinomas.
Rarer types Other infrequently seen types of renal cell carcinoma include medullary carcinoma; collecting duct RCC; multilocular cystic RCC; mucinous tubular and spindle cell carcinoma; and neuroblastoma-associated RCC.
In addition, some renal cell carcinomas are described as “unclassified,” either because they include more than one type of cancer cell or they don’t fit into any of the existing groupings.
Other Types of Kidney Cancer
Other types of kidney cancer include:
Transitional cell carcinoma Instead of starting in the kidney itself, these cancers start in the lining of the renal pelvis — the area where the ureters, tiny tubes that carry urine to the bladder, meet the kidneys.
Wilms tumor (nephroblastoma) This type of kidney cancer primarily affects children.
Renal sarcoma Renal sarcomas begin in the blood vessels or connective tissue of the kidney. They are rare, making up less than 1 percent of all kidney cancers.
While some people may notice symptoms of kidney cancer, others don’t experience any warning signs.
“The kidneys are located in the back of the abdomen, and tumors there can grow quite large without any symptoms at all,” explains Andrew J. Armstrong, MD, a professor of medicine, surgery, pharmacology, and cancer biology at Duke University School of Medicine in Durham, North Carolina.
Patients who do experience symptoms may notice:
Blood in the urine, which may look red, pink, or cola-colored
Doctors aren’t yet sure why kidney cancer develops. What they do know is that it begins with a mutation in the DNA of kidney cells that causes them to grow and divide rapidly in an uncontrolled manner. These abnormal cells create a tumor.
Risk factors that may increase the likelihood that someone will develop kidney cancer include:
Age Older people are more likely to develop kidney cancer, with the highest incidence between ages 55 and 84.
Smoking Smokers have double the risk of kidney cancer compared with nonsmokers.
Sex Men are about twice as likely as women to have kidney cancer.
Race Black people have a higher risk of kidney cancer than white people.
High blood pressure People with high blood pressure are more likely to have kidney cancer.
Obesity Research has shown an association between excess weight and kidney cancer.
Family history People with a family history of kidney cancer are more likely to develop the cancer themselves. Many of the genes associated with an increased risk of kidney cancer are linked to inherited disorders. These disorders include von Hippel-Lindau (VHL) disease, tuberous sclerosis complex, Birt-Hogg-Dube syndrome, hereditary papillary renal cell carcinoma, or familial renal cancer. When kidney cancer runs in families, it can lead to early onset in people under age 50. “Genetic testing is recommended in younger patients who are diagnosed with kidney cancers,” says Armstrong.
Kidney failure treatment Receiving long-term dialysis treatment for chronic kidney failure may raise a person’s risk for kidney cancer.
Occupational exposures Some studies have shown a link between exposure to cadmium or asbestos and kidney cancer.
Diagnosing kidney cancer can be tricky, particularly in patients who don’t experience symptoms. Studies show that more than half of kidney cancers are found by chance.
“Kidney cancer is often silent when present, and thus challenging to diagnose early. In fact, many cancers are picked up during CT or MRI scans being performed for other reasons,” says Dr. Armstrong. “Unfortunately, there are no recommended screening tests for asymptomatic patients, and this is needed.”
Tests
To rule out kidney cancer when there is a cause for concern, doctors typically recommend one or more of the following tests:
Physical exam This includes an exam to check for any unusual issues, as well as a review of the patient’s medical history.
Urine tests Urine samples are taken to see if they contain blood.
Blood tests Blood tests can help doctors determine if a person’s blood cell count and kidney function are normal.
Imaging tests Computed tomography (CT), magnetic resonance imaging (MRI), X-ray, and ultrasound may be used to look for kidney tumors or abnormalities.
Biopsy A small sample of tissue may be removed from a tumor to check for the presence of cancer cells. But biopsies for kidney cancer are not always accurate.
Staging Kidney Cancer
Part of formulating a diagnosis involves determining the extent of the cancer (a process called staging) so that doctors can devise the best treatment plan. Staging decisions are typically based on information that includes:
The size and location of the tumor
Whether and how much the cancer has spread to other tissues and organs
Whether and how much the lymph nodes — immune system structures that contain white blood cells — are affected
Doctors stage kidney cancer by assigning a numeral that ranges from 1 to 4. The lower the numeral, the less advanced the cancer. In about 25 percent of patients, kidney cancer has already spread to another area of the body at the time of diagnosis.
Which Medical Experts Diagnose and Treat Kidney Cancer?
The types of doctors who may be consulted in a kidney cancer diagnostic or treatment process include a:
Urologist A doctor with special training in treating diseases of the urinary system
Nephrologist A doctor who specializes in treating kidney conditions
Oncologist A doctor who treats cancer
Radiation oncologist A doctor who treats cancer with radiation therapy
Urologic oncologist An oncologist who specializes in diagnosing and treating cancers of the urinary system
Lee suggests finding a doctor with extensive experience treating kidney cancer.
“Even though kidney cancer is among the top 10 malignancies in terms of incidence, it is important to see a urologist and medical oncologist that has specific expertise with management of the disease who can help you determine whether standard treatments or a clinical trial would make the most sense for you,” says Dr. Lee.
Prognosis of Kidney Cancer
A patient’s prognosis will depend on how advanced the cancer is, the treatments they receive, their overall health, and other factors.
Kidney cancer is often curable if it is detected and treated early, before it breaks through the outer covering of the organ.
According to the National Cancer Institute, the relative five-year survival for all stages of kidney cancer combined is about 76 percent.
The duration of kidney cancer depends on the treatments a person receives and the stage of their disease.
If kidney cancer is caught very early, it may be cured with surgery. But many patients will have to undergo treatment for the rest of their lives.
Treatment options will depend on the stage of the disease, the patient’s overall health, the type of kidney cancer, and other factors. These options include:
Active surveillance If a kidney cancer tumor is very small, doctors might recommend actively monitoring the cancer without performing any type of treatment.
Surgery The most common treatment for people with kidney cancer is surgery. The two main types of surgical procedures are:
Nephrectomy Doctors remove the entire kidney, a healthy tissue margin, and sometimes, nearby tissues, such as lymph modes. Some nephrectomies can be performed using a single incision. Or surgeons may make small incisions in the abdomen, a procedure called laparoscopic or robotic-assisted laparoscopic nephrectomy. When one kidney is removed, the remaining kidney can usually perform the work of both kidneys.
Partial nephrectomy When the cancer is small, or if the patient has just one kidney, surgeons may recommend removing only the cancerous areas and a small margin of healthy tissue instead of the entire kidney. A partial nephrectomy can be performed as a traditional surgery requiring one incision, as a minimally invasive laparoscopic procedure, or as a robotic-assisted laparoscopic procedure.
Additional options Doctors sometimes eliminate small kidney tumors with procedures that use heat or cold. These treatments may be attractive alternatives for patients with other health issues that make surgery dangerous. They include:
Cryoablation A hollow needle is inserted through the skin and into the kidney to deliver cold gas to freezes and destroy cancer cells.
Radiofrequency ablation A probe is inserted through the skin and into the kidney to deliver an electrical current that heats and destroy cancer cells.
Radiation therapy High energy beams that kill cancer cells are sometimes used to manage kidney cancer that has spread to other areas of the body.
Medications for Kidney Cancer
Certain medicines may be options for people with kidney cancer who can’t be treated with surgery alone or who can’t tolerate surgery.
“In patients who are at high risk of recurrence of their disease, their urologist or oncologist can discuss whether adjuvant treatment or treatment with medications will decrease their risk of the disease coming back,” Lee says.
“Chemotherapy is generally ineffective for kidney cancer,” Armstrong says.
Medicines that are sometimes used for kidney cancer include:
Targeted therapies These drugs focus on blocking specific abnormalities in cancer cells. For kidney cancer, targeted therapies typically focus on tumor blood-vessel growth or the mTOR protein linked to the disease.
Immunotherapy A person’s own immune system can be triggered to fight cancer with medicines called immune checkpoint inhibitors, cytokines, and others.
Physical and emotional side effects of these treatment are not uncommon and vary according to which option is employed. In some cases side effects, such as gastrointestinal problems, may continue even after treatment has stopped. One important step people with kidney cancer can take to manage and potentially decrease side effects is to track the side effects and report them to their healthcare team.
Newer Treatments and Clinical Trials
Researchers continue to search for new ways to target and treat kidney cancers.
“Currently, we are working on developing new biomarkers that will help oncologists decide which treatment approach will provide the best outcomes for their patients,” says Lee.
“We are interested in developing novel pathways to attack the cancer. We are doing a lot of working to better understand how the genetics of the kidney cancer and the genetics of the patient impact the response to provide more personalized therapies, and we hope that in the future we will be able to develop more personalized approaches for patients,” he adds.
Clinical trials offer patients the chance to try some of the latest treatments being tested. Your doctor can help you determine if a clinical trial would benefit you.
There’s no one sure way to prevent kidney cancer, but certain lifestyle measures can help lower a person's risk of the disease. These measures include:
Minimize exposure to secondhand smoke and quit smoking if you do.
Avoid exposure to asbestos and cadmium.
Maintain a healthy weight.
Keep blood pressure levels under control.
“Because a lot of the medications that we use for kidney cancer can affect people’s heart or their sugars, it's important to reduce your risk of cardiovascular disease or diabetes, because these are risk factors that we need to consider when recommending treatment down the line,” notes Lee.
Kidney cancer can lead to complications, such as:
High blood pressure
High red blood cell counts
Elevated calcium in the blood
Liver or spleen issues
The cancer’s spread to other areas of the body can result in associated symptoms, such as buildup of fluid in the lungs or bone pain.
According to the American Cancer Society, about 79,000 new cases of kidney cancer will be diagnosed in 2022, and about 13,920 people will die of the disease.
New cases of kidney cancer have been steadily rising since the 1990s. Researchers aren’t sure why. One possible explanation is that newer imaging tests are picking up cancers that wouldn’t otherwise be detected.
Black Americans are more likely to develop renal cell carcinoma than white people, but the reason for the disparity is unclear. Though Black people typically present at an earlier stage in the disease, their survival rates are generally worse.
In a study published in the journal Cancer, researchers found the five-year relative survival rate for Black people with invasive kidney cancer was 68 percent compared with 72.6 percent for whites, regardless of sex, age, tumor size, tumor stage, the type of renal cell carcinoma, or the type of surgery performed.
Some research has suggested that genetic differences in tumors may contribute to poorer survival rates among Black patients with clear cell renal cell carcinoma.
Some conditions closely related to kidney cancer include:
A diagnosis of kidney cancer can be overwhelming for patients and their families. Staying up-to-date on research, participating in awareness campaigns, and joining support groups are some simple ways to cope with the disease. Here are some of Everyday Health’s top resources for people affected by kidney cancer.
