What people really say about cancer screening online: a look inside a Dutch discussion forum

Cancer screening programs work. Regular checks for breast, cervical, and colorectal cancer catch disease earlier, when treatment is more likely to succeed. Yet fewer people are showing up for them. Participation is dropping across the world, and in the Netherlands cervical screening uptake sits at around 46%, well below the 70% the World Health Organization says a program needs to make a real dent in cancer deaths.

So where do people go to make sense of an invitation letter for a smear test or a stool sample kit? Increasingly, online. We wanted to know what actually happens when people discuss cancer screening on the internet, not in theory but in practice, so we looked at fifteen years of conversation on one of the Netherlands' largest discussion forums.

Why a forum, and not social media

Most research on health misinformation looks at Twitter/X, Facebook, or Instagram. For this specific study, we chose something different: the Viva-forum, a Dutch forum that started life attached to a women's magazine, kept running by its users even after the magazine folded in 2021, and today still has close to 165,000 active members, most of them women between 18 and 70. That's roughly the age range targeted by Dutch breast and cervical screening programs, which made the forum a natural place to look.

Forums differ from social media in a way that matters here. They're organized into sections on specific topics, so people end up talking to others who share a concern rather than broadcasting to an open feed. Earlier research on stigmatized topics like postnatal depression has found that this setup makes people feel more understood by the people they're talking to. We wanted to know whether the same held for cancer screening, and what role misinformation played when it did.

We pulled threads from the forum's health section going back to 2010, searched for terms tied to Dutch screening programs, and worked through them by hand. After filtering out threads that used screening-related words but weren't actually about the national programs, we ended up with 361 threads to analyze in depth, using a mix of themes drawn from prior research and themes that emerged from the data itself.

People use the forum to hold each other up

The clearest pattern in the data was that users were, above almost everything else, supporting one another. We grouped what we saw into five recurring patterns: people told their own stories, offered practical information drawn from their own experience, gave each other emotional support, asked questions, and pointed each other to outside sources.

Storytelling was everywhere. Someone would describe finding out they had an early-stage cervical abnormality after a routine test, or the anxious wait for results that came back unclear. These weren't clinical case reports. They came with feeling attached, and people were open about being scared, relieved, or blindsided.

Practical, experience-based advice followed close behind. Someone who'd been through a colposcopy would walk a nervous first-timer through what to expect. This wasn't always glowing. Plenty of people voiced frustration, sometimes sharply, about specific aspects of the programs: why a follow-up procedure hurt more than expected, why men don't get invited for regular prostate checks the way women get invited for cervical checks, why screening only happens every five years instead of more often. What stood out is that this frustration was rarely aimed at the idea of screening itself. People wanted the programs to work better, not to go away.

And then there was plain reassurance. Somebody anxious about an upcoming test would get a reply along the lines of: it's over quickly, it's not as bad as you're picturing, you'll be fine. Small, but this kind of exchange is exactly what forums seem to be built for, and it lines up with older research showing that online support groups help people cope with a diagnosis or a scare.

Misinformation exists, but it's smaller and messier than expected

Given how much attention health misinformation gets, we expected to find plenty of it. We did find some. Out of 361 threads, 155 posts were flagged as potentially containing false claims. We brought in a medical doctor to help assess these, since judging medical accuracy isn't something you can do from a communication background alone. Of those 155, 55 turned out to actually contain incorrect information.

That's a smaller share than studies of cancer content on Twitter/X have reported, where researchers have found misinformation in roughly 4 in 10 of the most-liked cancer posts. Part of the difference may be the format. A forum thread invites back-and-forth, not a one-off post competing for likes.

What surprised us more was the shape the misinformation took. We'd expected mostly outright false claims, and about half of the flagged posts were that: for instance, a claim that women who've had breast augmentation are disproportionately dying of breast cancer, which isn't supported by evidence. But the other half was murkier. Some posts weren't wrong so much as missing nuance, or slightly off on a number, like citing 80% when the correct figure was closer to 85%. Others were personal guesses stated a little too confidently, with hedges attached, such as someone unsure whether breast implants complicate mammograms and saying so. And some posts revealed a simple mix-up between correlation and causation, like a comment linking height to cancer risk that reflects a real, if still not fully understood, statistical association, garbled into something closer to a mechanism.

This matters for how we think about the problem. If someone mixes a correlation with a cause, or misremembers a percentage, that's a different issue than someone deliberately spreading a falsehood. The people posting these things weren't necessarily trying to mislead anyone. Much of what we found looked less like intentional deception and more like people doing their best to recall details that experts spend careers getting precisely right, and getting the gist rather than the specifics, a pattern that researchers who study memory and health decisions have described as "gist-based" thinking, where people hold onto meaning while details drift.

We also found some claims that go further, closer to what shows up in wider health misinformation research: that mammograms themselves raise breast cancer risk through radiation exposure, that green tea can help prevent HPV, or that thermography (a heat-based imaging technique) works just as well as mammography and is more comfortable, so it should replace it. It doesn't; there's no good evidence it detects early-stage breast cancer as reliably. These sit closer to genuine misconceptions circulating more broadly online than to a simple memory slip.

The forum corrects itself, some of the time

Here's a finding we think matters most for anyone worried about online health misinformation: roughly four in ten misinformation posts we found were followed by a correction, written by another forum member, in the same thread.

The corrections came in different forms. Sometimes blunt: a user repeating the original claim word for word with "not" inserted or simply replying that what someone said wasn't true. Other times, someone would add the missing context. In one thread about HPV, after a post suggesting the virus is something you're just born carrying, another user stepped in to explain that HPV is sexually transmitted, that most people are exposed to it at some point, and that the immune system usually clears it on its own.

This kind of peer correction isn't hypothetical elsewhere either. Research on other platforms has shown that corrections from ordinary users, not just experts, can reduce misperceptions, partly because peer corrections don't carry the same defensiveness that a claim from an "official" source sometimes triggers. What we can now say is that this happens on a Dutch health forum too, without any intervention.

What this means going forward

None of this suggests forums are a substitute for a doctor's advice, and we didn't test whether reading these corrections actually changed anyone's mind. But we think the practical takeaway is that health communicators and screening organizations are underusing a resource that's already active and, to a real extent, self-correcting. Forums tend to get less monitoring attention than social media, but the conversations happening on them can reveal exactly which concerns and misconceptions are circulating among the people a screening program is trying to reach. We also saw healthcare professionals posting on the forum in their own voice, using their expertise to help other users directly, something we'd encourage more of.

There are limits to what we can conclude. We don't know what motivated any individual post; someone who is confidently wrong about a health fact could believe what they're saying, or could be posting in bad faith, and our data can't tell the two apart. We also relied on keyword searches to find relevant threads, so conversations that discussed screening without using our search terms would have been missed. Interviews with forum users, or newer computational methods that could scan a whole forum rather than a keyword-defined slice of it, would be a natural next step.

What we can say with more confidence is this: on this forum, over more than a decade, people mostly used cancer screening discussions to support each other, share what they'd learned from experience, and occasionally, when someone got something wrong, put it right themselves.