Is this a record?

In what may be the least accurate risk estimate ever published in a major newspaper, the Daily Mail said last week

• Hormone replacement could cause meningioma in menopausal women
• Those using HRT for a decade have a 70% chance of developing a tumour
• Most are benign but 15% are malignant and all have damaging side effects

You don’t actually need to look up any statistics to know this is wrong, just ask yourself how many women you know who had brain surgery. Hormone replacement therapy was pretty common (until it was shown not to prevent heart disease), so if 70% of women who used it for a decade ended up with meningioma, you’d know, at a minimum, several women who had brain surgery for cancer.  Do you?

In fact, according to the British NHS, the lifetime risk of meningioma is about 0.07%. Since it’s more common in women, that might be as much as 0.1% lifetime risk for women. The research quoted by the Mail actually found a relative risk of 1.7, so the lifetime risk might be up to 0.17% in women who take a decade of hormone replacement therapy. That is, the story overestimates the risk by 69.8 percentage points, or a factor of more than 400.

While this may be a record so far, there’s still room for improvement, and I certainly wouldn’t bet on the record standing for ever.

(via @hildabast and @BoraZ on Twitter, and Paul Raeburn of the MIT science journalism program)