Kidney cysts can be either simple or complex. The simple cysts are just fluid, can be drained and will never become cancerous. The complex cyst does have the ability to harbor cancer cells and requires vigilance.
Kidney cysts never cause to cancer. It is just benign and it never leads the cancer. Kidney cancer is caused by the kidney tumors. Cancer may cause because of the renal failure. There is no relation between the cyst and the cancer.