The cause of kidney cancer is unknown, but possible factors include: First, smoking, which is a relative risk factor for kidney cancer. Second, obesity and hypertension. Third, occupation, with reports indicating that long-term exposure to metallic lead, print industry workers, coke workers, and workers shows increased risks of incidence and mortality from kidney cancer. Fourth, radiation, where long-term exposure to certain sources of radiation may increase the risk of kidney cancer. Fifth, there is a certain relation to genetics. Sixth, dietary factors, as studies have found that high intake of dairy products, animal protein, and fat, and low intake of fruits and vegetables, are also risk factors for kidney cancer.