their even evidence suggests that oral cannabinoids are effective against nausea and vomiting caused by chemotherapy, and some small studies have found that smoked marijuana may also help to alleviate these symptoms Trusted Source. Some studies on cancer cells suggest that weed may either stall the development or eradicate some types of cancer. Nevertheless, early studies trusted Sources that tried this theory in humans revealed that although cannabinoids are a safe treatment, they are not effective at controlling or curing cancer.