Patients with a rare and aggressive form of liver cancer survived significantly longer when treated with medicinal cannabis, according to a study of 491 patients receiving palliative care in northeastern Thailand.
The study, published in F1000Research, found that those receiving cannabis treatment lived a median of 5.66 months after registration at palliative clinics, compared to just 0.83 months for patients receiving standard palliative care alone.
Combined hepatocellular‑cholangiocarcinoma (CCA), or bile duct cancer as it is more commonly known, is a very rare cancer which affects 0.59 in 1 million people globally.
In northern and north-eastern Thailand, there are over 100 times more instances of CCA than in the rest of the world. This is thought to be caused by a parasite called river fluke, which can be found in freshwater snails and fish that are often consumed raw or undercooked by people living in this area.
CCA is an aggressive and hard-to-treat cancer. Previous research shows the median survival time after diagnosis is nine months, with only 17 per cent of patients surviving past five years. For those without access to chemotherapy, the mean survival is just three to four weeks.
In the study, researchers retrospectively observed two groups of patients in palliative care with advanced-stage bile duct cancer. Of the 491 patients, 404 were receiving standard palliative care (ST), and the remaining 87 were receiving cannabis treatment (CT).
Most of the patients were already receiving either chemotherapy, palliative care, or a combination of both before they registered at the palliative care clinic.
After results were adjusted for covariables, the study showed that those in the ST group survived for an average of 0.83 months after registration, but survival in the CT group was measured at 5.66 months.
The researchers suggest several potential mechanisms for the improved survival observed in the cannabis treatment group. Cannabinoids may help indirectly by alleviating symptoms such as pain, loss of appetite, and nausea, which in turn could improve nutritional intake, sleep quality, and tolerance to systemic therapy.
Additionally, the study highlighted that preclinical studies have indicated potential anti-tumour effects, with cannabinoids showing the ability to induce cell death in cancer cells, inhibit blood vessel formation in tumours, and suppress tumour growth. However, the authors stressed that these mechanisms require validation through large-scale clinical trials.
“Taken together, the observed survival benefit in the CT group may be partly attributable to both patient- and treatment-related covariates, as well as the potential symptom-modulating and anti-tumor mechanisms of cannabinoids demonstrated in preclinical studies,” the study said. “This integrated interpretation underscores the multifactorial nature of survival outcomes in advanced CCA/HCC.”
