Experts are calling for the ongoing trial into extended breast cancer screening to be halted.
In a letter to The BMJ this week, Susan Bewley, Professor of Obstetrics at King's College London and colleagues describe flaws in governance and oversight that have led to "improper science and an unethical trial."
They call for the trial to be halted while an independent review is carried out.
A trial extending the ages at which UK women are eligible for breast cancer screening was registered in 2010. Currently, only women aged 50-70 are eligible for breast screening. This trial invites women for screening at ages 47-50 and 70-73.
Detailed scientific and ethical concerns have repeatedly been raised about the trial, say the authors. They point out that the chief investigator "is not medically or scientifically qualified, encourages contamination, ignores questions or obfuscates, and both runs the national programme and chairs the (non-independent) trial steering committee."
They highlight issues with the study protocol - and point to a 2012 independent review of breast cancer screening, which noted that the impact of breast screening outside the ages of 50-69 is uncertain.
Furthermore, they warn that women are not fully informed about the harms of overdiagnosis. "Thus, recruits cannot realise that it is uncertain whether breast screening works at their age or that research participation may carry risks. There is no assurance that they even realise they are in a randomised trial."
The age extension trial may be the largest ever human experiment, they say. "Lack of a proper research question and competence, inherent bias, and under-informed women have resulted in improper science and an unethical trial. We call for the age extension trial to be halted and for an independent review."