Benign and malignant tumors in kidneys and parts of the urinary tract affect more than 60,000 people in the United States each year.
Any type of growth, including one that’s benign, has the potential to affect how kidneys process and filter salts, waste products, and fluids through urination. The most common type of kidney cancer is renal cell carcinoma, which affects small tubes in one or both of the bean-shaped kidneys.
When caught early, many forms of kidney and urinary tract cancer respond well to treatment.
Causes and Risk Factors
It’s not clear what causes benign or malignant tumors to develop within kidneys or the urinary tract. What is known, however, is that there are several risk factors that can increase the risk of developing abnormal growths within this area of the body. Smoking, for instance, increases the odds of being affected by renal cell carcinoma. Excess weight may also cause certain hormonal changes that could contribute to the development of growths. Twice as likely to affect men, kidney cancer is also associated with the following risk factors:
- Long-term use of certain medications
- Being on long-term dialysis
- Exposure to certain herbicides and solvents
- Having advanced kidney disease
- High blood pressure
Signs and Symptoms
Patients in the early stages of kidney cancer may not notice any symptoms. As the tumor develops, it may contribute to a loss of appetite or weight loss for no apparent reason. Some patients may also experience extreme or lingering fatigue, anemia, blood in urine, ankle swelling, or fever. Larger tumors sometime produce a noticeable lump on the side or in the abdomen. If kidney cancer spreads to other parts of the body, it may cause shortness of breath and other respiratory issues or bone pain.
Diagnosing Kidney Cancer
Thirty to 40 percent of the time, smaller growths detected in kidneys or the urinary tract are benign. Larger tumors are more likely to be malignant. Diagnosis of a renal mass may involve urine and blood tests, a CT scan or MRI, or an intravenous pyelogram (IVP) performed with a special dye. The blood supply to the tumor may be tested with a renal arteriogram. Kidney cancer does not always require a biopsy to make a diagnosis, although a tissue sample may still be taken.
After a growth is discovered, initial treatment by a urologist usually involves follow-up image tests 3-6 months later. If the tumor isn’t changing in size or shape, continued observation may be all that’s necessary unless the growth is causing problems with the passage of urine. If the tumor is becoming larger or it’s cancerous, treatment may involve removal of the affected kidney, the adrenal gland, and nearby tissue (radical nephrectomy), removal of the kidney only (simple nephrectomy), or percutaneous cryoablation performed with a needle-like probe inserted through the skin. In rare instances, some patients experience spontaneous remission.
In the past, renal cancer was usually first detected when patients started to show clear signs of a problem such as blood in urine or abdominal pain. Today, kidney cancer is often detected with ultrasounds and similar image-based tests. A urology specialist may order such tests if a patient is reporting unusual symptoms that suggest something is going on in the urinary tract or kidneys.