Spend a few minutes surfing Twitter and you’re likely to encounter a startling claim that comes without proof:
Cannabis cures cancer.
The online world is awash with such posts, startling scientists and physicians who are urging marijuana proselytizers to hit the brakes.
“We know that a component in cannabis — CBD — might be useful in treating cancer,” said Dr. Joseph A. Califano III, director of the Head and Neck Cancer Center at the University of California, San Diego. “But we don’t know if marijuana can stop or cure it. In some cases, cannabis might make things worse....