Many governments and health agencies like to push mammography, despite the fact that it does not work so well. Not only does it benefit only a tiny fraction of women who undergo mammography, it can harm women too. One way it can do this is by picking up cancers that would not have bothered women over the courses of their lives if left alone. This, of course, exposes women to unnecessary treatment and often much anxiety.
Another potential consequence of mammography is that it can pick up ‘false positives’. Basically, suspicious lesions that turn out not to be cancer at all. One might argue that it’s better to be safe than sorry. But, even though I’m not a woman I’m reluctant to use this argument to negate the stress and anxiety of being recalled after a mammogram on the basis that something (not sure what) has been found and further investigations are required.
This week saw the publication of a study which sought to ascertain just how common false positives are as a result of regular mammography screening .
In the UK, current guidelines are for women to attend for a mammogram every three years from about the time they are 50 until their mid-70s. In the US, official guidelines are for mammograms to be done every two years. However, some ‘experts’ believe more frequent, annual, screens are better. While the official recommendation is for mammography to start at 50 in the US, some believe it should be commenced aged 40.
In this study, researchers calculated the percentage of American women who had a false positive test over a 10-year period.
- With screening every two years, 41.6 per cent of women had a false positive examination.
- With annual screening, this percentage was 61.3.
- About 8 per cent of women screen annually will go on to have an unnecessary biopsy too.
In addition to the anxiety such testing will usually induce, there is also the risk of scarring. And let’s not forget the cost.
I’m not against mammography. What bothers me is that women invited to attend for it are often not given the full facts. In general, the purported benefits are stressed, and the potential downsides not made plain to women. Earlier this year I wrote about a publication in which breast screening researchers accused scientists here in the UK of misleading women over the benefits and harms of mammography. In particular, there is a belief that pro-mammography scientists continue to cling to outdated concepts that more contemporary science proves to be incorrect. See here for more on this.
Whether a woman attends for mammography is a personal choice in the end. In my view it’s simply unethical to keep the best information we have from women for reasons that perhaps have to do with money and politics. Without the full facts, how are women to make an informed choice? It’s interesting to note that about half of American women just don’t have their mammograms as advised. As I speculated here, perhaps some of these women have educated themselves and learned stuff their government is not transparent about, and just decided mammography is not for them.
1. Hubbard RA, et al. Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study. Ann Intern Med. 2011;155(8):481-92