Kidney, or renal, cancer can occur in one or both kidneys. It strikes men more often than women, and is rarely found in people younger than 45 years old, says Yale Medicine pathologist Adebowale Adeniran, MD. About 16 per 100,000 men and women per year are diagnosed with kidney cancer in the United States each year. Pathological findings play an important role in diagnosing and identifying the most effective treatments for all kinds of renal cancer. 

Kidney cancer, also called renal cancer, is far more common in industrialized countries than less-developed ones. This is due in part to environmental factors including smoking, obesity and exposure to specific chemicals. “Symptoms can be vague, but most patients present with blood in the urine,” Dr. Adeniran says. “A significant proportion also have flank pain and, in cases where the cancer is advanced, fever and weight loss are common, too.”

The most common type of kidney cancer is renal cell carcinoma, which affects the tiny tubes (tubules) through which the kidneys filter blood. There are several types of renal cell carcinoma. “In the pathology department, our role is not only to determine whether a mass is cancerous or noncancerous,” Dr. Adeniran says. “For cancerous ones, we also need to be able to identify the type of malignancy we are looking at.”

If a patient’s symptoms suggest kidney cancer, and imaging tests, such as magnetic resonance imaging (MRI) or computerized tomography (CT) scans, reveal a kidney mass, a biopsy will be performed. A kidney biopsy is typically an outpatient procedure done under local anesthesia. The biopsy is then sent to pathology, where a diagnosis is made. This helps determine whether or not a patient needs resection, or removal of part of the kidney.

If a kidney biopsy indicates cancer, then the tumor is usually removed in a separate surgery. At Yale Medicine, kidney surgeries are accompanied by rapid intraoperative evaluation. This means that a pathologist is available during the surgery to examine tissue removed from the patient. The pathologist immediately performs tests to learn as much as possible about the tumor, including its size, the type of cancer, and the status of the cancer margins.

The pathology lab then performs further analysis on the tumor, gathering additional information that will help to shape treatment. “We measure the exact size of the tumor, which most of the time correlates with what was found from radiology,” Dr. Adeniran says. “We will describe the color of the tumor, because different kidney tumors have different coloration. For instance, clear cell renal cancer, the most common kind, almost always is golden yellow in color, so when we see that, we can identify it with a degree of certainty.”

Other factors provide insight into how aggressively the tumor is growing, how long it has been present, and what other parts of the body may be affected. A variety of stains are used to identify specific types of cells. Cytogenetic (chromosome typing) and molecular studies may provide additional data.

“The decision of how to treat a particular patient’s kidney cancer is based on what we tell the doctor about the biopsy,” Dr. Adeniran says. “If we know that a tumor is small and it is a less-aggressive type, we may not need to take out the entire kidney.” He says that some types of kidney cancer “tend to behave very well,” meaning that they don’t grow deep or quickly, and therefore don’t require the same aggressive therapy as other types. “We know that some tumors respond to a specific drug that targets that type of cancer,” he says. “This is especially important for us to know if a cancer is not operable because of a person’s age or other conditions.”

“Yale Medicine is unique in the sense that the people who are here are the best in their fields,” Dr. Adeniran says. “Our clinicians, urologists and pathologists have specialized training that allows us to make rare, specialized diagnoses.”

“Our state-of-the-art technology and equipment enable us to do molecular studies and immunostains that take the diagnosis to the cellular level,” he says. “We can then personalize the treatment to the patient in ways that can’t be done at most other places. Because of all this, we are leaders in the field.”

Yale Medicine also offers patients the ability to receive advanced therapies before they are widely available elsewhere. “Our pathologists and urologists and oncologists often participate in multi-institutional studies,” Dr. Adeniran says, “where we can try things out on a limited number of patients.”

Dr. Adeniran believes that Yale Medicine’s conferences – multidisciplinary gatherings where experts from all related specialties meet to present and discuss specific cases – are of great value. In many institutions, a pathologist’s job is done once a disease is diagnosed. But that’s not the case at Yale Medicine. “We don’t just make the diagnosis – how we treat the patient, and what we treat the patient with, depends on the diagnosis we pathologists make,” says Dr. Adeniran. “Here, we are part of the treatment.”