Infections causes 16% of cancers–what?

Ed Yong, a scientist and contributor to Discover Magazine, wrote an blog post, What does it mean to say that something causes 16% of cancers?, discussing a news report that stated that 16% of cancers around the world were caused by infections.  Here are some excerpts:

A few days ago, news reports claimed that 16 per cent of cancers around the world were caused by infections. This isn’t an especially new or controversial statement, as there’s clear evidence that some viruses, bacteria and parasites can cause cancer (think HPV, which we now have a vaccine against). It’s not inaccurate either. The paper that triggered the reports did indeed conclude that “of the 12.7 million new cancer cases that occurred in 2008, the population attributable fraction (PAF) for infectious agents was 16·1%”.

But for me, the reports aggravated an old itch. I used to work at a cancer charity. We used to get frequent requests we got for such numbers (e.g. how many cancers are caused by tobacco?). However, whenever such reports actually came out, we got a lot confused questions and comments. The problem is that many (most?) people have no idea what it actually means to say that X% of cancers are caused by something, where those numbers come from, or how they should be used. Continue reading “Infections causes 16% of cancers–what?”

Checking for pseudoscience in real science news (updated)

One of the larger problems of the internet (OK, there are a lot) is how science is discussed out in the world.  Google any science topic, and you’ll get thousand or millions of hits on any idea in science or medicine. The information is derived from other websites, news reports, rumors, or, to be cynical, from outright fabrication. In the fields of science and medicine, critical thinking is absolutely necessary to understanding it. Because it’s hard work, pseudoscience and anti-science have become quite prevalent lately.   Continue reading “Checking for pseudoscience in real science news (updated)”

Why do Americans hate Gardasil?

In next week’s issue of Forbes, Matthew Herper, the magazine’s medical editor, penned the article, The Gardasil Problem: How The U.S. Lost Faith In A Promising Vaccine, an insightful analysis of why Gardasil, the vaccine for human papillomavirus (HPV), has not become as important to vaccination strategies as measles or whooping cough.  All vaccines keep you alive, even if the disease does not appear to be scary.  There’s a belief, especially amongst the anti-vaccination crowd, that measles is just a few spots, and there are few risks to being infected.  The risk of severe complications is small, but significant.

On the other hand, the HPV vaccine does one thing and does it well–it prevents an HPV infection.  Human papillomavirus, a sexually transmitted disease, causes 70% of cervical cancers, 80% of anal cancers, 60% of vaginal cancers, and 40% of vulvar cancers.  It also prevents the majority of HPV caused oral cancers.  In other words, these diseases are in a different league of danger.  And they can be prevented. Continue reading “Why do Americans hate Gardasil?”

How pseudoscience makes its case. Part 4.

This is my continuing multi-part discussion about how pseudoscience uses logical fallacies, strawman arguments, and other rhetoric to make its case, rather than real science.  Just click on the links to read Part 1, Part 2, and Part 3.

The other day I engaged in a discussion with a well-meaning pharmacist who claimed that vitamin C could treat colds and prevent other diseases like  “cancer” (I always get annoyed  by people who lump all cancers together, when there are over 200 different cancers, all of which have different histologies, genetics, and causes).  Of course, there are a number of well-controlled clinical trials that show that vitamin C has no effect on the common cold and has no effect on cancers so far studied (see this, this, this and this).

During our discussion, she said “science should be neutral,” with the implication that I wasn’t neutral.  I happen to agree, science should be neutral and it should balanced.  But science should be based upon the scientific method not rhetoric and not using science-y words, at which the writers of Star Trek were well-versed.

So, when I say that I am (or any evidence-based real scientist), “scientifically neutral”, that means I’m willing to weigh the evidence and publications on real scientific issues.  I am not a geologist nor a paleontologist, but I was studying biochemistry when the earliest theories on what caused the Cretaceous-Tertiary extinction event 65.5 million years ago, where all the dinosaurs (well, not all, since technically modern birds are surviving dinosaurs from a cladistic point of view) and some 75% of all extant genera died out or were killed.  In 1980, Luis Alvarez, a brilliant theoretical physicist whose career was extraordinary, along with his son, Walter Alvarez (a geologist), and Frank Asaro, published an article that describe a sedimentary layer across the world that included a rare element, iridium, usually found in extraterrestrial objects like meteors and comets.  The layer fell right at the geological boundary layer that defines the extinction event, so they proposed that the dinosaurs were wiped out by a huge comet or asteroid.

Today, this accepted as a scientific theory with tons of confirming evidence (although some scientists aren’t fully convinced, though they still propose some natural event).  But at the time, it was ridiculed, and scientific meetings were quite energetic in discussions.  The point is that the impact theory displaced the prevailing scientific theory of the extinction event (well, there were several).  One theory replaced another not by rhetoric or appeals to antiquity (that one theory was around forever) or anything else.  In fact, one scientific hypothesis was replaced by another and eventually developed into a solid theory.

We should be neutral in science, reviewing the evidence, then coming to conclusions.  The Alvarez father-son team provided that, and eventually there was overwhelming evidence with the finding and dating of the Chicxulub impact crater in the Yucatan Peninsula of Mexico.

Using scientific neutrality, vitamin C doesn’t work, not because I have an opinion, but because there is no science supporting its efficacy.  There are some articles that support its use in preventing or treating colds, or megadoses for curing cancer, but those articles are in low-impact (meaning obscure) journals or with poorly designed, or non-blinded trials.  My friendly neighborhood pharmacist was stating that I should be neutral between real science and well, nothing at all.  That’s not balance, that’s a close-mindedness to science and the scientific method.  That’s using opinion as the balance to scientific knowledge.  The only thing that should balance scientific knowledge is more scientific knowledge.

Don’t fall for the trap that you should be “open-minded” or neutral to anti-science or pseudoscience.  Open-mindedness and neutrality are expectations that you will balance real scientific evidence, not treat the rhetoric as if it has equal weight to scientific method.