A friend is frightened by reading the headline “Chemotherapy may spread cancer and trigger more aggressive tumours, warn scientists” in the Daily Telegraph. A close friend of hers has had breast cancer successfully treated, but reading the headline, writes my friend, “fires me back to the very physical response I had [when her friend was first diagnosed with cancer]. A shattering feeling; like those goggles you wear at the Natural History Museum and it shows you how a butterfly sees in sickening circles. I have never had so physical a reaction to anything as I did to that news when it came. I would claw the floor.”
She emails me asking for my opinion, hoping obviously for reassurance.
The article says:
“It is thought the toxic medication switches on a repair mechanism in the body which ultimately allows tumours to grow back stronger. It also increases the number of ‘doorways’ on blood vessels which allow cancer to spread throughout the body.
He [there are actually 16 authors] also discovered that in mice, breast cancer chemotherapy increased the number of cancer cells circulating the body and in the lungs.”
I look at the paper in Science Translational Medicine, but I can access only the abstract, which contains no numbers and provides little opportunity for assessing the reliability of the findings, and what might be called “the plain language summary.” It says:
“Closing the door to cancer cells
Breast cancer is one of the most common tumor types, and metastasis greatly increases the risk of death from this disease. By studying the process of intravasation or entry of cells into the vasculature, Karagiannis et al. discovered that, in addition to killing tumor cells, chemotherapy treatment can also increase intravasation. Groups of cells collectively known as tumor microenvironment of metastasis (TMEM) can serve as gateways for tumor cells entering the vasculature, and the authors discovered that several types of chemotherapy can increase the amounts of TMEM complexes and circulating tumor cells in the bloodstream. The researchers also determined that a drug called rebastinib can interfere with TMEM activity and help overcome the increased risk of cancer cell dissemination.”
I was interested that the Daily Telegraph chose not to mention the drug and that it translated “intravasation” as “‘doorways’ on blood vessels.”
What is clear to me is that we need to be cautious in concluding anything much from this study, and I question the wisdom of the journal or medical school in press releasing such a study, which one or the other or both perhaps did.
How should I respond? I opted for the general followed by something more specific:
You should treat everything you read or hear about science in the media with great caution.
Similarly science itself should be treated with great caution. That’s what scientists do.
Science is not about truth but about hypotheses. You pose a hypothesis and then you try to test it to death, to falsify it, through experimentation. Just because you can’t falsify it doesn’t mean that it is true: it remains forever a provisional truth.
Unfortunately, scientists these days are assessed by how much and where they publish. This leads to excessive publication of provisional ideas, hypotheses. That’s one of the reasons for the finding of the paper “Why Most Published Research Findings Are False,” one of the most highly cited medical papers ever. It also accounts in part for what’s known as “the reproducibility crisis,” whereby around 80% of reported findings cannot be reproduced. Being able to reproduce experiments is fundamental in science, and yet scientists find it hard to find funding to do so and there are no rewards for such experiments.
Charles Darwin, as you probably know, waited years before he published Origin of Species; and, although his general ideas are right, some of what he wrote is wrong.
As you know from reading about politics and sport in the media, most of it is gossip, rumour, and speculation. It’s the same with science reporting, made easy by the fact that millions of scientific papers are published every year—most of them, as I’ve said wrong, but all of them ideas in evolution. Most journals these days put out press releases courting publicity.
So what you read in the media is speculative science amplified by a vast, ill functioning gossip machine—and usually exaggerated for impact.
That’s why you shouldn’t pay much attention to any report.
To turn to the specific, we know that chemotherapy in breast cancer improves survival. Many, many clinical trials combined into systematic reviews have shown that. This is close to being a “truth.”
These trials are, however, about populations of women, and overall they do better. Some women within the population might do worse. One of the biggest challenges in medicine is to try and relate the individual to the population, and that is the promise (still mostly a promise rather than a reality) of “personalised medicine” based on genes.
Neither you nor your friend should be frightened by this piece. It may well amount to nothing, and even if it does it will apply to only some women–because we know that overall chemotherapy is beneficial.”
I don’t think that my general ramblings were helpful to my friend. She honed in simply on the sentence: “To turn to the specific, we know that chemotherapy in breast cancer improves survival.”
GPs regularly have the problem of having to respond to media reports, and unlike me they have to do it face to face, often without the full paper, and always without the time (and training) to assess it fully. It must be tempting to dismiss all media reports, but perhaps my general response, which stops short of complete dismissal, could be helpful.
Richard Smith was the editor of The BMJ until 2004.
Competing interest: None declared.