Most kidney cancers are now found by accident on scans taken for something else
Early kidney tumours usually cause no symptoms and cannot be felt during an examination. Yet more than 60 percent of renal cell carcinomas, the commonest type, are now spotted incidentally, on ultrasound or CT scans ordered for vague abdominal complaints. That matters, because survival depends heavily on how far the cancer has spread.
The label covers several distinct cancers arising in the kidney. Renal cell carcinoma makes up about 80 percent of cases and is thought to arise in the tubules that filter blood. Transitional cell cancer, which begins in the lining of the renal pelvis where urine collects, accounts for most of the rest and behaves more like bladder cancer. In children, the usual form is Wilms' tumour, an embryonic cancer. Later on, the textbook trio is bloody urine, pain in the side or back, and a mass that can be felt.
Globally it newly affected about 403,300 people in 2018 and caused 175,000 deaths, ranking as the 13th most common cancer. It usually appears after age 45, has been rising since 1930 and is more common in cities than the countryside. Known risk factors include smoking, obesity, high blood pressure, family history, long-term dialysis and hepatitis C. Smoking is linked to roughly a quarter to a third of cases, with risk climbing with the number of cigarettes and dropping substantially a decade after quitting.
Imaging does most of the diagnostic work. CT with and without contrast dye is the standard way to find and stage a tumour, with MRI as an alternative, and doctors look chiefly at whether a mass takes up contrast. Biopsy is reliable for confirming cancer, with a positive result correct 99.8 percent of the time, but a negative one cannot rule it out. The lungs are the most common place for it to spread.
Surgery is the main treatment because kidney cancer responds poorly to chemotherapy and radiation, and many tumours can be removed while sparing the rest of the kidney. Overall five-year survival is 78 percent in the United States, but that figure hides a steep gradient by stage.
Source: Kidney cancer
