katek here is an extract from an article published in the Guardian, on 10 things doctors wouldn't do. It's Professor Susan Bewley, professor of complex obstetrics at Kings College Hospital, on why she wouldn't have a screening mammogram:
"I won't go for a screening mammogram. Down the microscope, doctors can't always tell the difference between "dangerous" and "OK to leave alone". So it is possible to find things "too early" that are not really life-threatening cancer. The independent review of breast cancer screening published last year in the Lancet helpfully distinguished biases, uncertainties and some bad science. The latest quantification is that of every 10,000 women screened every three years from age 50-70, about 43 fewer will die from breast cancer. Approximately 700 will be given a cancer diagnosis and a whole lot more women will be frightened by being recalled for further tests. Although most women who are told they have cancer by screening are grateful, I wouldn't be sure whether my life was really "saved" or if I'd just become an extra cancer patient.
It appears that for every 15 women who are "screen-diagnosed", three will still die of breast cancer (so screening doesn't save their lives), eight will still live (so screening brought the diagnosis earlier, but treatment would have worked anyway), one will not die of breast cancer (so screening prevents this cause of death) but three extra will become "cancer victims" (so screening leads to having surgery and/or radiotherapy/chemotherapy that wouldn't have happened in her lifetime). Screening can only be credited with one woman not dying of breast cancer, but all 15 have to be treated once something is found. It's complicated enough to understand, and some women will take these odds. But I'm happy to wait until I have symptoms."
Susan Bewley, Professor of Complex Obstetrics, King's College London