Marijuana May Be an Effective Therapy for Lung Cancer

Researchers at Harvard University report that THC, the active ingredient in marijuana, reduces lung cancer tumor growth by at least 50%, and also reduces the ability of the lung cancer tumors to metastasize, or spread, to other areas. These findings are being reported at the current annual meeting of the American Association for Cancer Research, in Los Angeles, CA.

Delta-tetrahydrocannabinol (THC), the key hallucinogenic compound in marijuana, was found to inhibit non-small cell lung cancer by targeting and binding to the cells' cannabinoid receptors CB1 and CB2. The body can naturally produce a class of compounds similar in function to THC, called endocannabinoids, which also bind the same receptors. When CB1 and CB2 are bound, they are less responsive to the effects of epidermal growth factor (EGF), a compound involved in the growth, survival, proliferation, and differentiation of mammalian cells. Since lung tumors that over-express the receptor for EGF are aggressive, and usually unresponsive to chemotherapy, blockage of this pathway by THC or similar compounds may become one therapeutic option for cancer patients.

Anju Preet, one of the researchers conducting this study, tested lung cancer cell lines and patient tumor samples by treating them with non-lethal doses of THC, finding that the substance prevented their growth and spread. Preet and her colleagues then implanted mice with tumors derived from lung cancer patients and injected the mice with THC for three weeks. The tumors shrunk by at least 50% in the animals injected with THC, compared with controls. There was also a significant reduction in protein markers found associated with tumor growth and metastasis.