Cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) – two key compounds found in cannabis – demonstrate significant anti-cancer effects against ovarian cancer cells when used in combination, according to new research published in Frontiers in Pharmacology.
Researchers at Khon Kaen University in Thailand tested the compounds on two ovarian cancer cell lines and found that CBD and THC together significantly inhibited cell growth, reduced colony formation and limited cancer cell migration. Crucially, the treatment caused minimal harm to healthy cells, suggesting that it could be used safely as a treatment.
“Ovarian cancer remains one of the deadliest gynecological malignancies, characterised by late diagnosis, high recurrence rates and limited effective treatment options,” said Dr Siyao Tong, lead author of the study. “Our goal is to find alternative drugs that can improve efficacy and potentially reduce toxicity, ultimately bringing new hope to patients facing this challenging disease.”
The research team tested CBD and THC individually and in combination on ovarian cancer cells. When used together in a 1:1 ratio, the compounds produced the strongest effects, demonstrating what the researchers describe as synergistic action.
The study revealed that the combination treatment worked by restoring control over the PI3K/AKT/mTOR pathway – a signalling system often overactivated in ovarian cancer that contributes to tumour progression and drug resistance. By returning this pathway to more normal activity, the cannabis compounds reduced growth and increased cell death in cancer cells.
Additional experiments showed that the compounds reduced cancer cell migration, an important finding given that metastasis remains a major cause of death in ovarian cancer patients. A therapy that limits the spread of cancer could significantly improve outcomes.
Importantly, both platinum-resistant and platinum-sensitive ovarian cancer cells responded similarly to treatment. Platinum resistance is a major clinical problem as platinum-based drugs (like cisplatin and carboplatin) are the standard first-line treatment for ovarian cancer. However, many patients develop resistance to these drugs over time. The treatments also caused little harm to healthy cells, indicating that future therapies based on these compounds might be easier for patients to tolerate than many current options.
“Although our study is still preliminary, it lays an important foundation for future research into the potential applications of CBD and THC in ovarian cancer treatment,” Dr Tong emphasised. “By confirming their anti-cancer activity and identifying key molecular mechanisms, our findings are expected to drive further preclinical research.”
The researchers emphasised that the study has significant limitations that must be addressed before cannabis can be used medically to treat ovarian cancer. “The results may not fully reflect the complexity of tumour behaviour in living organisms,” Dr Tong acknowledged. “We did not include in vivo models and pharmacokinetic data, which are crucial for determining whether CBD/THC can be safely and effectively used clinically.”
Ovarian cancer causes more deaths than any other gynaecological disease. According to Cancer Research UK, there are 7,600 new cases of ovarian cancer each year, with a 39.3% survival rate over 10 or more years. Despite advances in treatment, available drugs often fail to produce long-lasting results and can cause severe side effects, making the search for new therapeutic approaches urgent.
