When it comes to beating cancer, treatments such as chemotherapy and radiation are proven, effective and relatively safe for patients. Yet nearly 40 percent of Americans believe alternative medicine alone can stop the disease in its tracks. That’s according to the American Society of Clinical Oncology’s (ASCO) latest National Cancer Opinion Survey, Healthline reports.

The finding suggests that many people still don’t know the facts about getting well.

Alternative treatments are those used instead of conventional treatment; complementary, or integrative, treatments are those used alongside standard treatment.

The survey of 4,887 adults ages 18 and older in the United States asked about a variety of alternative treatments, including herbal supplements, oxygen therapy, special diets or other vitamin supplements. It found that young people between ages 18 and 37 were the most likely to believe that alternative medicine alone could cure cancer, while adults ages 72 and older were the least likely. More than one in five of those surveyed currently have or have had cancer; among this group, 22 percent thought alternative therapies trumped standard care. 

The reality, experts warn, is simply that on their own, alternative treatments do not work, and, worse, sometimes can be dangerous. Multiple studies show that people who turn down evidence-based cancer treatment in favor of alternative therapies are up to 2.5 times more likely to die in a given period than those who follow their doctors’ recommendations. What’s more, the vast majority of alternative therapies haven’t been rigorously tested and those that have been don’t offer any benefits. 

“This study comes as a bit of a wake-up call to physicians” said Jose Carillo, MD, PhD, a neuro-oncologist and associate professor at the John Wayne Cancer Institute at Providence Saint John’s Health Center in California. “I’ve seen patients [switch to alternative medicine] many times in the past, only to see their tumor come back aggressively despite their best intentions.” 

So how can doctors combat the misinformation? Studies show that between 48 and 88 percent of cancer patients use some form of complementary or alternative medicine as part of their care. Researchers say it’s important for doctors to ask about such treatments and work with their patients to determine what’s best for them, urge them toward standard treatment and—critically—know everything they’re taking. 

That said, some complementary therapies have been proved effective. For example, studies show that acupuncture may help alleviate the nausea that often accompanies chemotherapy as well as some of the pain associated with cancer. Yoga can help relieve anxiety and depression. And medical marijuana has also proved beneficial for alleviating various symptoms in many cancer patients.

Ultimately, says ASCO, doctors need to better educate their cancer patients and build trust in order to improve communication and not just dispense treatment.