The cause of kidney cancer is unknown. However, the incidence of this cancer is rising, possibly as a result of exposure to environmental carcinogens as well as increased longevity. Even so, kidney cancer accounts for only about 2% of all adult cancers. It’s twice as common in men as in women and usually affects patients older than age 40.

Kidney cancer produces a classic triad of signs and symptoms—hematuria, pain, and a palpable mass—but any one may be the first indication of cancer. Microscopic or gross hematuria (which may be intermittent) suggests that the cancer has spread to the renal pelvis.

Constant abdominal or flank pain may be dull or, if the cancer causes bleeding or blood clots, acute and colicky. The mass is generally smooth, firm, and nontender. All three signs of kidney cancer coexist in only about 10% of patients.