Does the internet have a cancer-faking problem? So asks a recent article in The Atlantic that takes a look at Munchausen by internet, a phenomenon that’s rattling online support groups for people facing cancer.

On social media and online, people in support groups and on crowdfunding sites are frequently discovered to be healthy and cancer-free—though researchers say it is difficult to say how pervasive the phenomenon is. However, a number of recent high-profile cases have highlighted the issue.

In 2015, wellness blogger Belle Gibson admitted she lied about a brain cancer diagnosis for years. In 2018, GoFundMe campaigner Candace Ann Streng was sentenced to up to 15 years in prison after pretending to have terminal cancer and accepting nearly $30,000 in online donations. In February, a New Yorker profile alleged that the best-selling author Dan Mallory lied to several colleagues about having brain tumors, which Mallory later claimed he’d done to disguise his struggles with bipolar disorder.

Munchausen by internet, also known as MBI, is an online version of the mental disorder formerly known as Munchausen syndrome, in which people feign illness or actually make themselves sick for attention. The term MBI was originally coined in 2000 by psychiatrist Marc Feldman, who wrote that the anonymity of the internet can make such lies far more common than the estimated 1% of hospitalized patients thought to be faking an illness.

“The internet makes it easier to portray ourselves as something we are not,” said Dawn Branley-Bell, PhD, a psychologist at Northumbria University who studies extreme online behaviors and commented on the report. “Trolls often justify their actions by saying the online world is not ‘real life,’ so it doesn’t matter what they do or say online. It is possible some users refuse to believe their [actions] online have real, psychological effects on others.”

Experts also believe people with MBI may gravitate toward lying about cancer in particular because the disease is so common, often lacks signs in its early stages, can recur and affects anyone of any age or any gender.

So what’s an online cancer support group to do when faced with someone suspected of having MBI? In most groups, administrators act only when presented with evidence by members, who often cross-post their findings to other members or groups for confirmation. The motivation of those caught faking cancer are rarely investigated (users are usually just get kicked out of their respective support groups). However, faking cancer can have serious consequences, especially when donations or expensive services are involved.

That said, most online cancer groups take people at their word about their condition, welcoming those in search of a community with open arms. That’s a good thing, say cancer patients and advocates, and something that should remain a cornerstone of effective support.