Cannabinoids, the group of active compounds found in cannabis, are currently getting a great deal of attention from researchers for their potential medical applications. Despite many studies still being in their nascent stages, early observations are showing these compounds can decrease the growth of cancerous tumors. A new study has found pairing cannabinoids with chemotherapy drugs can increase the tumor-killing effects of both.

A team of oncologists at the University of London studying the effects of cannabinoids on leukemia cells in vitro, has observed that not only did cannabinoids enhance the death of cancer cells when used in combination with chemotherapy drugs, but the order in which the compounds were administered was vitally important.

The cannabinoids were only effective in enhancing the treatment when administered after chemotherapy. The study reports that when the order was reversed, with the cannabinoids being administered before the chemotherapy, the effect was significantly diminished.

"We have shown for the first time that the order in which cannabinoids and chemotherapy are used is crucial in determining the overall effectiveness of this treatment," explains Dr Wai Liu, who led the study.

We are still in the very early stages of clinical research into the broader effects of cannabinoids on cancer, and it's important to remember that this study was only performed in vitro and animal studies are yet to come. The researchers also note that these results do not mean that smoking marijuana has any particular anti-cancer effect.

"These extracts are highly concentrated and purified, so smoking marijuana will not have a similar effect," adds Dr Liu.

The long term goals of research like this could result in cannabinoids enhancing the effect of lower doses of chemotherapy, meaning current treatments would be more efficacious with fewer side-effects. More studies are currently underway exploring the potential medical uses of cannabinoids, but it is possible that oncologists could soon have a new weapon in their arsenal to battle cancer.

The study was published in the International Journal of Oncology.