Ovarian cancer is one of the hardest cancers to catch and one of the hardest to treat. By the time most women receive a diagnosis, the disease has already spread, and the drugs available today often fall short. Side effects are brutal. Recurrence rates are high. And for too many patients, the options run out long before the fight is over. But a research team in Thailand just published results that caught the attention of scientists around the world. They tested two well-known compounds found in cannabis on ovarian cancer cells, and what happened surprised even the researchers. Something in the combination triggered a response that current drugs have struggled to produce. And the healthy cells nearby? They were left almost entirely alone.
Ovarian Cancer: A Silent and Stubborn Killer
Among all gynecological cancers, ovarian cancer causes the most deaths. It earns that grim ranking because of how difficult it is to detect early. Most women have no clear symptoms until the cancer has reached an advanced stage. By then, it has often spread beyond the ovaries to the abdomen, lymph nodes, or distant organs.
Even when doctors catch it, treatment options are limited. Platinum-based chemotherapy drugs are the standard first-line approach. While they can shrink tumors, many patients develop resistance over time, which means the same drugs stop working. Recurrence is common. And the side effects of chemotherapy, ranging from nausea and fatigue to nerve damage and immune suppression, take a heavy toll on quality of life.
Dr. Siyao Tong of Khon Kaen University in Thailand, who led the new study, put it plainly: ovarian cancer remains one of the deadliest gynecological cancers, marked by late diagnosis, high recurrence rates, and limited effective treatment options. Her team set out to find alternative drugs that could improve effectiveness and reduce toxicity, bringing new hope to patients facing a disease with few good answers.
Why Researchers Turned to Cannabis
Cannabis has a long history in medicine, though most of its modern medical use centers on symptom relief. Cancer patients often use cannabis products to manage pain, nausea, and appetite loss caused by chemotherapy. But in recent years, laboratory studies have hinted that certain compounds in cannabis may do more than ease symptoms. They may actually fight cancer cells directly.
Two compounds drew the attention of Tong’s research group: cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC). CBD is the non-psychoactive compound in cannabis, meaning it does not produce a “high.” THC is the psychoactive component responsible for the altered mental state people associate with marijuana use.
Both compounds had shown signs of anti-cancer activity in studies on other cancer types. But their effects on ovarian cancer cells, especially when used together, had not been well studied. Tong’s team wanted to know: could CBD and THC, individually or combined, kill ovarian cancer cells? And would they spare healthy tissue in the process?
What Happened in the Lab
Researchers tested CBD and THC on two different ovarian cancer cell lines. One cell line was sensitive to platinum-based drugs. The second was resistant, mimicking the kind of treatment-resistant cancer that makes ovarian cancer so hard to manage. They also tested the compounds on healthy cells to see if normal tissue would suffer damage.
Each compound was tested alone at various doses, and then the two were combined at different ratios. When used individually, both CBD and THC slowed cancer cell growth and reduced the number and size of cancer cell colonies. But neither compound alone killed large numbers of cancer cells. The real surprise came when the two compounds were combined.
A 1:1 Ratio That Changed Everything
When researchers mixed CBD and THC at a one-to-one ratio, the effects jumped dramatically. Cancer cells died at much higher rates. Colony formation dropped sharply. And the cancer cells lost much of their ability to migrate, a finding that matters because metastasis (the spread of cancer to other parts of the body) is what makes ovarian cancer so lethal.
Tong noted that the inhibitory effect was most pronounced when CBD and THC were used at equal doses. Something about the combination created a synergistic response, where the two compounds working together produced a stronger effect than either could achieve on its own. Scientists believe CBD and THC may attack cancer cells through different biological mechanisms that reinforce each other when combined.
Both the platinum-sensitive and platinum-resistant cancer cell lines responded to the treatment. If those results hold up in future studies, it would mean the combination could work across multiple ovarian cancer types, including the drug-resistant forms that leave patients with few remaining options.
Healthy Cells Were Left Alone
One of the most encouraging findings was the treatment’s selectivity. While the CBD and THC combination killed ovarian cancer cells at high rates, it caused minimal harm to healthy cells. Selective toxicity is one of the most sought-after qualities in cancer treatment, because most chemotherapy drugs destroy healthy and cancerous tissue alike, causing the severe side effects patients dread.
A treatment that preferentially targets cancer cells while sparing normal tissue could mean fewer side effects, better quality of life during treatment, and potentially higher doses without increased risk. For ovarian cancer patients who have endured rounds of harsh chemotherapy, a less toxic option would represent a meaningful change.
How It Works: Shutting Down a Cancer Growth Pathway
To understand why the CBD and THC combination was so effective, Tong’s team looked at what was happening inside the cancer cells at a molecular level. They focused on a signaling pathway called PI3K/AKT/mTOR.
In healthy cells, this pathway helps regulate growth, survival, and metabolism. But in many ovarian cancers, the PI3K/AKT/mTOR pathway becomes overactive. When it runs unchecked, it drives tumor growth, helps cancer cells resist drug treatment, and supports metastasis.
After treating ovarian cancer cells with the CBD and THC combination, researchers observed that activity in the PI3K/AKT/mTOR pathway decreased. Phosphorylation, the chemical process that keeps the pathway switched on, dropped across key proteins in the chain. At the same time, levels of a tumor-suppressor protein increased, suggesting that a natural braking system the cancer had disabled was being restored.
In simple terms, the cannabis compounds appeared to flip the cancer’s growth switch back toward “off” while turning its natural defenses back “on.” If future research confirms this mechanism, it could open a clear path toward targeted drug development based on these compounds.
What This Does Not Mean (Yet)
Before anyone rushes to draw conclusions, several important caveats need to be stated clearly. All of this research was conducted in vitro, meaning it took place in lab dishes, not in living organisms. Cancer cells in a dish behave differently from tumors growing inside a human body, surrounded by blood vessels, immune cells, and complex tissue environments.
No animal studies have been completed. No human clinical trials have been run. And no pharmacokinetic data exists to show how CBD and THC behave inside the body when used at anti-cancer doses, whether they reach tumors in sufficient concentration, how long they remain active, or what side effects might appear at therapeutic levels.
Tong was candid about these limitations. She acknowledged that the results may not fully reflect the complexity of tumor behavior in living organisms and that regulatory and legal issues surrounding cannabinoid therapy could also affect future research. In short these results are promising, not proven. They are a starting point, not a finish line.
Why Early Results Still Matter
Despite the caveats, this research fills a gap that oncology has long needed to address. Ovarian cancer treatment has not changed dramatically in decades. Platinum drugs remain the backbone of care, and when they stop working, patients face a shrinking list of options.
Finding compounds that kill drug-resistant cancer cells, spare healthy tissue, and work through a well-understood biological mechanism is exactly the kind of lead that drives drug development forward. Each piece of evidence moves the science closer to a viable treatment.
Tong and her team plan to continue their research with preclinical animal models and deeper molecular analysis. If future studies confirm the safety and effectiveness of CBD and THC against ovarian tumors in living systems, clinical trials in human patients could follow.
For the millions of women diagnosed with ovarian cancer each year, any credible new direction for treatment is worth watching closely.
My Personal RX on Supporting Women’s Health and Cancer Prevention
Ovarian cancer often goes undetected until advanced stages, making prevention and early awareness all the more important. While no lifestyle change can guarantee you will never face a cancer diagnosis, keeping your body well-nourished, rested, and resilient gives your immune system the best chance at catching problems early. I tell my patients that cancer prevention starts with daily habits, not a single test or supplement. Here is what I recommend:
- Prioritize Deep Sleep Every Night: Your body performs critical repair and immune functions during deep sleep. Sleep Max contains magnesium, GABA, 5-HTP, and taurine to calm your mind, balance neurotransmitters, and promote restorative REM sleep so your body can do its repair work overnight.
- Know Your Nutrient Gaps After 40: Age-related nutrient decline weakens immune defenses and energy levels. Download my free guide, The 7 Supplements You Can’t Live Without, to learn which supplements your body needs most, which “healthy” foods may be misleading you, and how to identify quality products worth your investment.
- Move Your Body for at Least 30 Minutes Daily: Regular physical activity reduces inflammation, supports healthy hormone levels, and improves immune function. Walking, swimming, yoga, or cycling all count toward keeping your body in a cancer-resistant state.
- Reduce Processed Food and Sugar Intake: High-sugar diets promote insulin resistance and chronic inflammation, both of which are linked to increased cancer risk. Replace processed snacks with whole fruits, vegetables, nuts, and seeds.
- Know Your Family History: If ovarian, breast, or colon cancer runs in your family, share that information with your doctor. Genetic counseling and earlier screening can catch problems when they are still treatable.
- Do Not Ignore Persistent Symptoms: Bloating that does not go away, pelvic pain, changes in appetite, and urinary urgency can all signal ovarian problems. Bring these symptoms to your doctor rather than dismissing them as stress or aging.
- Limit Alcohol Consumption: Alcohol raises estrogen levels and promotes inflammation, both of which increase cancer risk in women. Reducing intake supports hormonal balance and overall cellular health.
- Schedule Annual Gynecological Exams: Regular visits with your OB-GYN give your doctor the best chance to catch changes early. Pelvic exams, transvaginal ultrasounds, and CA-125 blood tests can be part of a monitoring plan if you are at higher risk.
Source: Tong, S., Loilome, W., Namwat, N., Klanrit, P., Wangwiwatsin, A., Win, Z. Z., Koyabuth, P., & Chumworathayi, B. (2025). Selective anti-cancer effects of cannabidiol and Δ9-tetrahydrocannabinol via PI3K/AKT/mTOR inhibition and PTEN restoration in ovarian cancer cells. Frontiers in Pharmacology, 16, 1693129. https://doi.org/10.3389/fphar.2025.1693129
Subscribe to Ask Dr. Nandi YouTube Channel
