Breast cancer – to screen or not to screen – Part 2 – Zoë Harcombe

Executive summary

* This is the second of a two part note trying to answer the question – breast cancer – to screen or not to screen?

* The research was prompted by an invitation to screening that I received. The accompanying booklet reported the key trade off as “for every 1 woman who has her life saved from breast cancer, about 3 women are diagnosed with a cancer that would never have become life threatening.”

* As no lives are going to be saved (we’re all going to die), I wanted to know by how much might the 1 woman ‘saved’ have her life extended and by how much might the 3 women harmed have their life shortened. How many women would be screened and not saved or harmed?

* Part 2 explains the source of 3 key numbers in the screening debate:

– the 1,300 lives saved;

– the 1 saved for 3 overdiagnosed;

– the claimed life extension.

* My question was not fully answered, as I still don’t know by how much women treated unnecessarily have had their lives shortened. If screening has extended the life of 1 woman by X years and reduced the life expectancy of 3 women together by more than X years, it has net harm.

* Part 2 shares additional findings from my research into this topic:

– The average age of women dying from breast cancer;

– Doubt over the 1,300 lives saved estimate, because the outcome from real trial data was multiples different to this number;

– Mortality from all cancer and all-causes, not just deaths attributed to breast cancer;

– Lump size, doubling times and the lump size that screening can detect;

– Personal attacks on scientists questioning the value of mammography.

* Finally, I share my decision – to screen or not to screen – and how I reached it.