A team of US researchers has used artificial intelligence to comb through more than 10,000 cannabis and cancer studies, finding that a substantial majority of the evidence pointed to better outcomes for patients using the medicine.
The study, published in Frontiers in Oncology, applied a technique known as sentiment analysis to categorise thousands of studies according to whether their conclusions on cannabis as a cancer treatment were positive, neutral or negative.
Lead author and research director at the Whole Health Oncology Institute (WHOI), Ryan Castle, told The Guardian: "Our goal was to determine the scientific consensus on the topic of medical cannabis, a field that has long been dominated by a war between cherrypicked studies."
The project was backed by Cancer Playbook, an organisation that collaborates with WHOI to gather, examine and publish patient-reported outcome data. Researchers drew on both observational studies and laboratory research examining the relationship between medical cannabis and cancer.
Castle said: "In order to move beyond bias – conscious or not – it was essential to use a large-scale, radically inclusive methodology based on mathematical reasoning. We wanted to analyse not just a handful, but nearly every major medical cannabis study to find the actual points of scientific agreement."
Although the team had hoped to confirm "moderate consensus" around cannabis as a tool for managing cancer symptoms, Castle said the final results surpassed their "best-case scenario" of 55%.
"It wasn't 55-45 [reporting improved outcomes], it was 75-25," he said.
The analysis backed the medicine's potential in addressing cancer-related inflammation, appetite loss and nausea.
"That's a shocking degree of consensus in public health research, and certainly more than we were anticipating for a topic as controversial as medical cannabis," Castle added.
The Guardian reported that the study "also showed that cannabis has the potential to fight cancer cells themselves, by killing them and stopping their spread", while acknowledging that such claims are still contested and have not been proven.
Castle said he hoped the results would push the US Drug Enforcement Administration to finalise its long-stalled process of reclassifying cannabis away from its current status as a federally illegal substance, which would open the door to more clinical research.
"We are not arguing that the standards for adopting new cancer treatments should be lower," he said. "We are arguing that medical cannabis meets or exceeds those standards, often to a greater extent than current pharmaceutical treatments."