Why kidney cancer is often found by accident and what to watch for

Kidney cancer is often called a "silent" disease, and for many patients because it's discovered unexpectedly, without any warning signs.

"Most kidney cancer is now diagnosed incidentally on imaging," says Herbert Ruckle, MD, FACS, chair of urology at Loma Linda University Health. "With how much imaging we do today such as CT scans, MRIs, ultrasounds, we're finding tumors that otherwise may have gone unnoticed."

In many cases, the cancer isn't found because of symptoms, but during scans for unrelated concerns such as back pain, injury, or other routine evaluations.

A cancer often without warning signs

Unlike many cancers, kidney tumors can grow quietly without causing symptoms. In many cases, patients feel completely healthy when cancer is discovered.

"People may come in for something unrelated like back pain, abdominal discomfort, or even imaging after an injury, and that's when a mass is found," Ruckle says.

Because of this, early-stage kidney cancer is frequently caught by chance rather than through screening or symptom-driven visits.

Still, when symptoms do appear, they shouldn't be ignored. Blood in the urine, whether visible or microscopic, is one of the most important warning signs and should always be evaluated.

Why more cases are being diagnosed

About 80,000 new cases of kidney and renal pelvis cancers are diagnosed each year in the United States, with men affected more often than women.

Over time, the number of diagnosed cases has steadily increased, nearly tripling since the 1970s, and there are two main factors driving that trend.

"One is increased imaging; we're simply finding more tumors," Ruckle says. "The second is lifestyle factors, like obesity and high blood pressure."

These risk factors are becoming more common nationwide, contributing to a higher likelihood of developing kidney cancer over time.

Better outcomes when caught early

Despite the challenges in detecting kidney cancer early, outcomes are encouraging, especially when tumors are found before they spread.

The five-year survival rate for all types of kidney cancer is approximately 80%, highlighting the importance of early diagnosis and timely treatment by an experienced team.

Even when symptoms aren't present, routine medical care and appropriate imaging can play a critical role in catching the disease earlier.

What patients should know

While there is no standard screening test for kidney cancer, awareness of risk factors and attention to unusual symptoms, such as blood in the urine or persistent flank pain, can help prompt earlier evaluation.

"It's something we're often finding and able to treat before patients even know it's there," Ruckle says.

To learn more about kidney cancer care or to schedule an evaluation, visit Loma Linda University Health or speak with your primary care provider about your risk factors.