Let's Talk About Kidney Cancer Symptoms

It’s hard to spot a disease when there are few signs that anything could be wrong. We asked the experts what to look for when it comes to kidney cancer.

by Lexi Krupp Health Writer

Like most cancers, kidney cancer is infinitely easier to treat if it’s caught in its earliest stages. But most people with kidney cancer don’t have clear symptoms and it’s often not until they have another medical procedure that a doctor sees something that doesn’t look right. Still, there are sometimes a few clues that your kidneys may be under stress. Here’s what symptoms can crop up, and what to expect if doctors do find something abnormal.

Kidney Cancer Symptoms

Our Pro Panel

We went to some of the nation’s top experts on kidney cancer to bring you the most up-to-date information possible.

Pedro Barata, M.D. headshot
Pedro Barata, M.D.

Pedro Barata, M.D.

Medical Oncologist

Tulane Cancer Center

New Orleans, LA

Katy Beckerman, M.D, Ph.D.
Katy Beckerman, M.D, Ph.D.

Katy Beckerman, M.D, Ph.D.

Medical Oncologist

Vanderbilt University Medical Center

Nashville, TN

Benjamin Chung, M.D. headshot.
Benjamin Chung, M.D.

Benjamin Chung, M.D.

Director of Robotic Surgery and Urologic Oncologist

Stanford University Medical Center

Stanford, CA

Kidney Cancer Symptoms
Frequently Asked Questions
Can I be screened for kidney cancer?

In short, no. There’s no lab test to diagnose kidney cancer. But if you’re at high risk because of family history or show suspicious symptoms, doctors will run imaging tests to look for a growth in your kidneys.

How do I know if I have kidney cancer?

The only way to confirm kidney cancer is to remove a piece of the tumor, either with a biopsy or surgery, and look at the cells under a microscope, but imaging tests can give doctors a good idea of what looks like cancer.

Can doctors tell how long a tumor has been growing?

There’s no way to know if a cancer has been slowly forming in a kidney for years or just popped up. Kidney cancers may grow a few millimeters each year, or swell to several centimeters in under a year, often depending on the type of cancer.

Why don’t doctors use PET scans to look for kidney cancer?

Although these imaging tests work well to detect some other types of cancer, they don’t usually pick up kidney cancers because many tumors won’t take up the dye used in a PET scan. Instead, CT scans or MRIs are the best imaging tests to look for kidney cancer.

What Is Kidney Cancer Again?

About 70,000 Americans are diagnosed with kidney cancer every year. All told, nearly half a million people in the U.S. are living with the disease. But unless you’re one of them, you probably haven’t spent a whole lot of time thinking about what your kidneys are and how they work.

So here’s the deal. When we talk about your kidneys, we’re referring to two fist-size organs that hang out behind your gut. Their job has four parts:

  • Filter waste products from your blood

  • Maintain fluid balance in the body and make pee

  • Help control your blood pressure

  • Produce hormones that maintain strong bones and keep your red blood cell count in check

Tiny pipes called tubules inside each kidney serve as the workspace for the blood-cleaning action to happen—and they’re also the spot where cancer is most likely to develop. In fact, about 90% of kidney cancers begin when a mass forms in these blood-filtering tubes. When a mass grows in the kidneys and continues to spread, it’s considered cancerous. The type of cancer you have often changes what treatment options work best, but different kidney cancers can look the same on imaging tests and cause similar symptoms.

Difficulty in Diagnosing Kidney Cancer

The tricky thing about kidney cancer is that early on in this disease, you may have no symptoms at all. And unlike, say, a lump in the breast, kidney tumors are deep inside the body and just a few centimeters long in the early stages, meaning you probably won’t physically feel it, either.

Also, there are no recommended screening tests for people at average risk of developing kidney cancer. Doctors don’t suggest it simply because none of the tests have shown to lower your odds of dying from the disease.

Instead, doctors often find kidney tumors while doing imaging tests for an unrelated health problem. While many of the tumors found by chance are relatively small and slow-growing, some will have already spread to other parts of the body.

Keep in mind, growths in the kidney aren’t always cancer—they can be fluid-filled cysts or tumors that won’t spread to other organs—but your doctor will want to investigate any suspicious-looking lumps anyway.

What Are the Symptoms of Kidney Cancer?

Most people with this disease won’t have any obvious indicators of kidney cancer when they are diagnosed. Still, around a third of people do receive a diagnosis because of their symptoms, which often appear in more advanced stages, though not always. If you have symptoms from kidney cancer, here’s what can show up:

  • Pain in the lower back, often on one side. Pain in the area between your ribs and hips is one of the more common experiences in patients who have symptoms. It might occur when a tumor has grown large enough to invade nearby organs or mess with how you pee.

  • Blood in your pee. Another more common sign of kidney cancer, blood in your urine (technically known as hematuria) doesn’t necessarily mean you have bright red pee (although it’s possible). The color can also look pink or rusty, or blood might only be visible under a microscope.

    Also, the issue may come and go, so you might think the problem has taken care of itself—until it comes back again. A urinary tract infection, kidney stone, and a handful of other problems can cause red blood cells to appear in your pee as well, so this isn’t a sure sign of cancer, but you’ll definitely want to get it checked out.

  • A lump at the bottom of your rib cage. If a tumor grows to be large enough, you or your doctor might be able to feel it just below your rib cage. But because your kidneys are far inside the body, you won’t be able to feel a small tumor.

  • Swollen legs and ankles. If a tumor prevents your kidney from doing its job of removing excess fluid from the blood, it’s possible that you may experience water retention and swelling in your legs and ankles.

  • Swelling in the scrotum (varicocele). In a very small percentage of men, kidney tumors can block the veins leading from the testicles, causing inflammation and pain in the scrotum, usually on the left side.

  • Unexplained weight loss. A lot of things can cause you to lose weight, from a bout of the flu to stress to a change in your diet. But if you haven’t changed things up and aren’t feeling under the weather, weight loss may be an indication of illness, including cancer.

  • Fevers and night sweats. In response to kidney cancer, your immune system may trigger a fever that comes and goes over several weeks. If you have an enduring, unexplained fever that appears intermittently, you should consult a doctor.

  • Anemia. People with kidney cancer may be diagnosed with anemia, the clinical term for having low levels of red blood cells. Here’s what happens: When you’re healthy, your kidneys normally produce a hormone called erythropoietin, which tells your bone marrow to make red blood cells. In turn, these cells help transport oxygen to other cells in your body. But kidney cancer can interfere with the production of erythropoietin, lowering your red blood cell count and minimizing the flow of oxygen throughout your body.

  • Extreme fatigue. Due to the low red blood cell count or other changes wrought by cancer, extreme fatigue is a possible symptom. This isn’t the same as the is-it-Friday-yet tiredness many people feel during the week. We’re talking about a stretch of days or weeks where you struggle to make it through your day without feeling exhausted. If just getting out of bed and making yourself breakfast leaves you totally wiped, it’s a sign something may be up with your health.

  • High blood pressure. Among the hormones your kidneys normally produce, renin is one that helps regulate your blood pressure. When a tumor is present, it may cause your kidneys to increase the production of renin, making your blood pressure rise. Tumors may also create blockades in the blood vessels, another source of high blood pressure.

How Do Doctors Diagnose Kidney Cancer?

If kidney cancer is a possibility, your doctor will conduct a physical exam, collect your medical history, run blood and urine samples, and do an imaging test—typically a computed tomography (CT) scan of the abdomen, to determine the size, shape, and location of a tumor.

If you’re allergic to the dye used in a CT scan, have limited kidney function, or if your doctor suspects a tumor has crept up one of the major veins leading from the kidney, they might perform a magnetic resonance imaging (MRI) instead. And if there’s concern that the cancer has spread outside the kidney because of other symptoms, your doctor will run additional imaging tests, often checking your chest, bones, or brain.

There’s no way to know for sure if someone has kidney cancer without examining the tumor cells under a microscope. For that reason, your doctor may also perform a biopsy—a procedure where a small piece of the tumor is removed with a needle, guided by an ultrasound or CT scan, and then examined in a lab to determine the type of cells involved. In other cases, your physician may recommend surgery to remove the tumor.

But because imaging tests can give doctors a good idea of whether or not a mass is cancerous, a biopsy isn’t the norm for most patients. What’s more, tumors can be made up of many different types of cells (some cancerous, and some not) that a biopsy won’t capture. So in general, doctors only perform biopsies if the outcome would change their treatment decisions.

Living With Kidney Cancer

Although there are few obvious signs of kidney cancer early on, most people catch the disease in its earliest stages, when it’s still only located in the kidney. At this point, the five-year relative survival rate, or people who live more than five years after their kidney cancer diagnosis, is 93%, and many remain disease free.

Around a third of patients are diagnosed by the time the disease has spread beyond the kidney to other organs. That makes treatment more challenging—but still possible. Researchers have made major advanced in the last few years to treat advanced kidney cancer.

What’s more, fatalities from kidney cancer have fallen by 1% every year since 2008, largely because of improved detection and treatment. So if you’ve been diagnosed—look, it’s no walk in the park. But neither is it a death sentence, provided you seek out treatment and work with your medical team on a plan back to good health.

Lexi Krupp
Meet Our Writer
Lexi Krupp

Lexi Krupp is a journalist who covers health and science stories for audio and print. Before moving to New York City, she taught ecology in Wisconsin and Maine.