A cannabis-based flavonoid pharmaceutical composition including any one or more selected from among the group of Cannflavin A, Cannflavin B. Cannflavin C, Chrysoeriol, Cosmosiin, Flavocannabiside and their derivatives selected from among the group of Geraldol, Rhamnetin, Isorhamnetin, Rhamnazin, or their synthases, for the prevention and treatment of certain cancers that can be treated by therapeutically targeting oncogenic factors including kinases, sirtuins, bromodomains, matrix metalloproteinases and histone acetylases. Some of the cancers that can be treated by use of cannabis flavonoids based on the inhibition of these therapeutic targets include but are not limited to brain, breast, colon, renal liver, lung, pancreatic, pigmented villonodular synovitis, prostate, leukemia, melanomam, tenosynovial giant cell tumor, as well as any other cancers that overexpress the oncogenic factors inhibited, by the cannabis flavonoids or their derivatives herein identified.