Kidney Cancer: Everything You Need to Know

Let’s start with the basics. Your kidneys are two potato-shaped organs that sit behind your belly on either side of the spine. They filter your blood—straining out salt, water, and other chemicals—and turn the waste into pee.

This blood-cleaning action takes place in tiny pipes called tubules inside each kidney, and that’s where the trouble with cancer usually pops up. In about nine out of 10 kidney cancer patients, the cancer begins when a mass forms in these blood-filtering tubes.

 

We don’t know the full story of what causes kidney cancer, but we understand a few pieces of the puzzle, especially for more common forms of the disease.

In most cases, kidney cancer begins when there are mutations in certain genes that normally keep cell division in check. When this system isn’t working properly, new cells grow at abnormal rates and can amass into tumors, which can then grow and spread. For example, people with clear cell renal cell carcinoma often have a mutation that causes extra blood vessels to grow inside the kidney.

Most kidney cancer patients acquire these mutations over their lifetime, meaning they’re born with perfectly healthy genes controlling cell division, but as they age, a cell’s genetic code changes. When the cell reproduces, that quirk in the genetic code spreads. Notably, these changes usually occur in conjunction with other factors before cancer shows up.

Other people inherit certain conditions from their parents that increase their risk of developing various types of kidney cancer. Many of these people will have tumors in other organs in their body and are more likely to be diagnosed with kidney cancer in their younger years. Here are a few of those inherited disorders:

• Von Hippel-Lindau disease

• Hereditary papillary renal carcinoma

• Birt Hogg-Dubé (BHD)

• Hereditary leiomyoma (HLRCC)

• Succinate dehydrogenase deficiency

• Tuberous sclerosis

• PTEN hamartoma tumor syndrome (including Cowden syndrome)

If you have kidney cancer, ask your provider if you should consider genetic counseling, particularly if you’re diagnosed before you’re 47, have tumors on both kidneys, or if you have a family history of kidney cancer. This will determine if you have one of these genetic conditions that could raise the risk of developing cancer for other family members. Or, if you have already been diagnosed with one of these conditions, talk with your doc about your increased risk for kidney cancer.

Who Gets Kidney Cancer?

Cancerous growths can invade kidneys of people at any age, who are otherwise healthy, but some folks have a greater chance of developing kidney cancer than others. Here are a few risk factors for the most common types of kidney cancer:

• Gender: Men make up more than 60% of kidney cancer patients.

• Age: Most people are diagnosed as older adults, between the ages of 55 and 74.

• Smoking: Men who smoke are about 50% more likely to develop kidney cancer; women have close to a 20% increased risk from smoking. Scientists don’t understand exactly how smoking spurs cancer, but they do know that the risk of cancer drops the longer you stop.

• Obesity: People who are obese are 20% to 30% more likely to develop kidney cancer. Research to understand this connection is ongoing.

• High blood pressure: This can double the risk of kidney cancer, according to a number of studies.

• Family history: About 5% of patients have other family members with kidney cancer or certain inherited conditions that put them at higher risk.

• Kidney disease: People living with chronic kidney disease and those on long-term dialysis (when a machine filters your blood) have a greater risk of developing kidney cancer.

• Environmental exposures: Working with certain chemicals including trichloroethylene (often used as a solvent to remove grease), asbestos, benzene, benzidine, cadmium, herbicides, and vinyl chloride increases the risk of developing kidney cancer.

Kidney cancer can be frustratingly sneaky. The majority of people don’t have any symptoms when they get a diagnosis. Instead, most learn of a mass on their kidney when they’re seeing their doctor for an unrelated issue that requires an imaging procedure. If doctors see something suspicious, they can follow up with a CT scan or an MRI to get a better look at the kidney.

People often don’t experience symptoms until the cancer has advanced, although that’s not always the case. For those with symptoms (about a third of patients at diagnosis), here’s what can show up:

Related to your kidneys:

• Pain in your low back, often on one side

• Blood in your pee

• A lump around your low rib cage

• Swelling in the scrotum (varicocele)

Your whole body:

• Weight loss

• Fevers and night sweats

• Tiredness

• Low red blood cell count

• High blood pressure

There are more than a dozen types of kidney cancer, and knowing what type you have is important to figuring out what treatments will work best for you. Your cancer type will also help predict how the disease might progress.

In all likelihood, if you are diagnosed with kidney cancer, it’s probably going to fall under the category known as renal cell carcinoma. The vast majority of kidney cancers belong to this category, meaning the cancer shows up in the main chunk of the kidney, where the organ filters blood.

Within renal cell carcinomas, there are sub-types of cancers that differ depending on what the tumor cells look like under a microscope. These sub-types are divided into clear cell RCC (common) and non-clear cell RCC (less common). Here are the three most common types of renal cell carcinomas:

Clear Cell

• Accounts for between 70 to 80% of renal cell carcinomas.

• Aptly named, these tumor cells look transparent when magnified. Because it’s the most common type, clear cell renal cell carcinoma (RCC) is one of the best understood kidney cancers and treatment options are fairly well established.

• This type of kidney cancer can come back years or even decades after treatment.

• If clear cell RCC spreads outside the kidneys, it can pop up anywhere in the body, but it is most likely to be found in the lungs, liver, brain, or bones.

Papillary

• Makes up 10% to 20% of renal cell carcinomas.

• These cells look pink underneath a microscope and form long, finger-like shapes inside a tumor. There are two types of papillary RCC: Type 1 tends to be slow-growing and confined to the kidney. Type 2 is often more aggressive and likely to spread to other organs.

Chromophone

• Responsible for 5% of renal cell carcinomas.

• The cells in chromophone RCC are also pale, but larger than clear cell RCC.

• Tumors are often slow-growing and don’t typically spread outside the kidney.

Rare Renal Cell Carcinomas

In addition to the common types of renal cell carcinomas, there are multiple rare types of the disease that each make up less than 1% of all kidney cancers. If you have a rare form of kidney cancer, your doctor will likely suggest seeing a specialist to get the best possible treatment.

• Acquired Cystic Disease–Associated RCC: This rare cancer exclusively shows up in patients with end-stage kidney disease.

• Collecting Duct Tumors: This aggressive disease is usually diagnosed in young adults at an advanced stage of cancer, typically with poor prognosis

• Mucinous Tubular and Spindle Cell Carcinoma: An extremely rare form, this cancer is more often found in women, and is typically slow-growing.

• Neuroblastoma-Associated RCC: This disease is only found in survivors of certain childhood cancers that affect immature nerve cells or the adrenal glands.

• Renal Medullary Carcinoma: An extremely aggressive cancer, RMC is found in patients with sickle cell trait and related diseases, and often affects kids and young adults.