An Unpleasant Surprise

CURE, Spring 2006, Volume 5, Issue 1

With no standard screening test for kidney cancer and few symptoms until it’s advanced, early-stage disease is often discovered by accident when imaging scans, such as computed tomography, are used to look for other medical problems.

With no standard screening test for kidney cancer and few symptoms until it’s advanced, early-stage disease is often discovered by accident when imaging scans, such as computed tomography, are used to look for other medical problems.

There is actually a term sometimes used—incidentalomas, meaning incidentally picking up a kidney tumor,” says David M. Nanus, MD, medical director of the genitourinary oncology program and co-division chief of the hematology and medical oncology division at Weill Medical College of Cornell University and New York Presbyterian Hospital. “Patients get CT scans to investigate a variety of abdominal pains, which turn out to be a virus or nothing. But then the scan happens to show a tumor in your kidney.” This increasing scenario is because of the more prevalent use of imaging scans, including CT, MRI (magnetic resonance imaging), and ultrasound.

Use of imaging scans to screen for cancer is currently being researched in lung, ovarian, prostate, and colorectal cancers, but not kidney cancer. Surprisingly, some patients in clinical trials are being told not that they have a suspicious shadow on their lungs, but on their kidneys, often catching the disease in its early stages.

Small studies have shown that patients with incidentally diagnosed kidney cancers usually have early-stage disease, resulting in higher overall survival than symptomatic patients. Early-stage kidney cancer patients also have a 95 percent chance of 10-year survival compared with patients who have advanced kidney cancer and a less than 20 percent chance of surviving two years.

Many kidney cancers are diagnosed in late-stage disease because of indistinct or absent symptoms. Usually only seen microscopically during a urine analysis, blood in the urine is a common symptom of kidney cancer, but it can also be caused by kidney stones, bladder and urinary tract infections, or benign enlargement of the prostate. The good news is most physicians conduct a urine analysis once a year for patients to detect problems in the genitourinary area.

Pain also presents in late-stage disease when kidney tumors begin to press on nerves or organs. Other symptoms, such as weight loss, fever, and sweats can be attributed to many other diseases besides kidney cancer, further delaying diagnosis. “Kidney cancers can manifest in many different ways to general internists, making it difficult to diagnose,” says Nanus, but imaging has made it easier to find tumors, even when physicians aren’t looking for them.

CT scans have become the gold standard to diagnose kidney cancer and, unlike other screening tests, kidney cancer screens have a low rate of false-positives. But oncologists aren’t recommending the scan for patients who have no symptoms, even if they have risk factors associated with the disease, such as smoking, high blood pressure, or obesity. “There are no data in kidney cancer or other tumors to show that it’s cost-effective or beneficial to screen asymptomatic patients,” says Nanus. “Sometimes it raises more problems than it solves."