Unclear question. Some benign tumors predispose to malignant tumors, e.g. Colon polyps, and moles. Most benign tumors do not become malignant. There is no such entity as benign cancer.
Nomenclature. Confusing! "benign cancer" is a contradiction in terms, but there are benign tumors (can grow huge but can't invade or spread), and there are cancers (like basal cell of the skin or many bladder cancers) that are slow and pose little short-term danger. There are genetic disease with multiple benign & malignant tumors; otherwise, tumors occur depending on risk factors and dumb luck.