Once again mammography screening is put under the spot light, this time it’s the US charity Susan G Komen overstating the benefits of mammography and ignoring the harm it causes. Authors of a BMJ Observations paper state:
“If there were an Oscar for misleading statistics, using survival statistics to judge the benefit of screening would win a lifetime achievement award hands down. There is no way to disentangle lead time and overdiagnosis biased from screening survival data.”
Professors Steven Woloshin and Lisa Schwarz point out that the ‘lead time’ * and overdiagnosis means there is ‘no correlation between changes in survival and what really matters, changes in how many people die’.
The authors calculate the actual benefit from mammography is a reduction of only 0.07% percentage points for a woman in her 50’s dying from breast cancer over a 10 year period.
Overdiagnosis in the US means that for means that for every woman who’s life is ‘saved’ by mammography, around 2 to 10 women are over diagnosed. The risk from overdiagnoses (those women diagnosed that would never have developed symptoms or died from breast cancer) is women receive invasive, potentially harmful and unnecessary chemotherapy, radiation or surgery.
The situation is similar here in the UK with regard to mammography been sold as to help reduce mortality.
“Early detection makes treatment more likely to be effective and helps to reduce mortality. By bringing forward detection and diagnosis, screening helps us find those cancers that might otherwise not be caught until later in life .”
The NHS screening program boasts a 45% rise in the number of women attending screening.
The figures from the UK cancer establishment state that that one life will be saved for every 2,000 women screened for 10 years. About 7 breast cancers are found for every 1,000 women screened as part of the UK breast screening programme.
What the BMJ paper does not go into is that mammography is radiation, a carcinogen even at low levels. Surely it’s about time we have safer and truly accurate detection methods for breast cancer and abolish the myth that screening saves lives and focus instead on primary prevention? When will we stop using carcinogens to detect cancer?
The BMJ Press Release can be found here
Link to pay per view paper
* The lead time in relation to breast cancer is compared to watching a train approach with binoculars, it doesn’t speed up the arrival, it just means you can see (diagnose) the train when its much further away