One study looked at the effects of CBD and THC in 177 people with cancer-related pain who did not experience relief from pain medication.

Those treated with an extract containing both compounds experienced a significant reduction in pain compared to those who received only THC extract (Trusted Source).

CBD may also help reduce chemotherapy-induced nausea and vomiting, which are among the most common chemotherapy-related side effects for those with cancer (Trusted Source).

Though there are drugs that help with these distressing symptoms, they are sometimes ineffective, leading some people to seek alternatives. A study of 16 people undergoing chemotherapy found that a one-to-one combination of CBD and THC administered via mouth spray reduced chemotherapy-related nausea and vomiting better than standard treatment alone.

Some test-tube and animal studies have even shown that CBD may have anticancer properties. For example, one test-tube study found that concentrated CBD induced cell death in human breast cancer cells. Another study showed that CBD inhibited the spread of aggressive breast cancer cells in mice.

However, these are test-tube and animal studies, so they can only suggest what might work in people. More studies in humans are needed before conclusions can be made.