Black seed oil is also thought to have anticancer properties. It may help fight against skin cancers when applied topically.Portions of black seed oil known as thymoquinone and other seed potions were able to reduce the growth of tumors in lab rats. The oil also may help to reduce the tissue damaging effects of radiation that is used to kill cancer cells. But these results haven’t been studied in humans. Black seed oil shouldn’t be used as a substitute for conventional cancer treatments.