Is breast cancer screening worth it?
Participating in breast cancer screening may offer a small benefit, but the chance of unnecessary treatment or a false-positive result is real. Consider what matters most to you, and discuss it with your GP if you are unsure.
Mammography screening reduces the chance of dying from breast cancer, but the effect is smaller than is often assumed. The best randomised trials combined show a relative reduction of 15 to 25 percent, but when you look only at the most carefully designed studies, this effect cannot be demonstrated statistically. In absolute terms: for every 1,000 women invited who participate from the age of fifty for twenty years, an average of 2 to 3 deaths from breast cancer are prevented. For overall life expectancy, counting all causes of death, there is no demonstrable difference.
There is a considerable price to pay. Overdiagnosis is the greatest harm: a substantial proportion of the tumours detected, with estimates ranging from 20 to 50 percent of cases, would never have caused symptoms or death without screening. Those women are treated anyway, with surgery, radiation and side effects they would never have experienced without screening. In addition, women who participate undergo breast surgery significantly more often, including mastectomy more often, than women who do not participate.
False-positive results are another common drawback. Over 10 years of screening, roughly 1 in 5 participants receives a result that requires further investigation, while no cancer ultimately turns out to be present. This leads to demonstrable anxiety and uncertainty that sometimes persists for years.
For women younger than 50, an effect on mortality has not been demonstrated and the balance between benefit and harm is even less favourable there. For women over 74, randomised studies are entirely lacking; other diseases that become more common at older ages reduce the potential benefit while increasing the risk of unnecessary treatment. An individual conversation is therefore more appropriate than a standard invitation.
Finally, the information women receive with their invitation systematically overstates the benefits and frequently omits the harms. Genuinely informed choice begins with honest figures, covering both the possible gain and the real chance of overdiagnosis and a false-positive result.
This answer draws on several systematic reviews and a meta-analysis of randomised trials, so it represents the best available summary of existing research. The estimates of overdiagnosis are the least certain: the figures vary widely between studies, and researchers disagree on the correct method for calculating overdiagnosis. The effect on breast cancer mortality is plausible but not statistically significant in the best-designed studies, indicating that it is a modest and uncertain effect. Evidence on women over 74 and women under 50 is thin.
Should you get tested for hereditary breast cancer?
Breast cancer can be hereditary, and if you recognise multiple cases in your family, it is sensible to discuss this with your GP or a genetic counsellor to decide whether testing makes sense for you.
Which cancer screenings are worthwhile, and from what age?
Colorectal cancer screening from age 50 and mammography from age 40 have the best evidence base for the average person; lung cancer screening is only relevant if you have a heavy smoking history. Other screenings are only worthwhile in the presence of specific risk factors or inherited conditions.
Should I, as a man, be tested for prostate cancer with the PSA test?
Whether the PSA test is worthwhile depends on your personal risk. Men aged 55 to 69 with an elevated risk, such as a family history or Black background, have the most reason to discuss this with their GP.
Does bowel cancer screening really help (fewer deaths)?
For people between 45 and 75 with an average risk, bowel cancer screening is worthwhile and widely recommended. It demonstrably lowers the chance of developing bowel cancer, although the evidence for reducing deaths in the short term is less definitive than previously thought.
Is a full-body MRI scan worthwhile as a preventive measure?
For people without an elevated cancer risk, a full-body MRI scan is not currently recommended: evidence that the scan saves lives is lacking, and the chance of unnecessary follow-up investigations is real. If you have a strongly elevated hereditary risk, discuss with your doctor whether the scan makes sense for you.
Does being overweight increase my risk of cancer, and if so, which types?
Excess weight increases your risk of at least 13 types of cancer, including uterine, colorectal, breast and liver cancer. Losing weight reduces that risk, although it remains unclear whether all methods of weight loss are equally effective for immune defence against cancer.