How has Marijuana been helpful?
THC and marijuana are promoted to relieve pain, control nausea and vomiting, and stimulate appetite in people with cancer and AIDS. Researchers also report that THC decreases pressure within the eyes, therefore reducing the severity of glaucoma.
Some supporters claim that marijuana has anti-bacterial properties, inhibits tumor growth, and enlarges the airways, which they believe can ease the severity of asthma attacks. Others claim that marijuana can be used to control seizures and muscle spasms in people who have epilepsy and spinal cord injuries.

http://www.cancer.org/treatment/treatmentsandsideeffects/complementaryandalternativemedicine/herbsvitaminsandminerals/marijuana