Re: Cost of extending the NHS breast screening age range in England
Alexandra Barratt suggests that a strong trial design could address the question of overdiagnosis. However, cessation of screening will lead to a decrease in the observed cancer incidence as a consequence of reverse lead time, because cancers are detected in advance during screening. An accurate interpretation of lead time is necessary before trying to evaluate overdiagnosis. When this is done, it is found that overdiagnosis is much less of an explanation of the increased incidence of cancer after national screening was implemented than breast cancer caused by the radiation of screening mammography (1). Thus, the group without screening after the age of 70 years will not show a large difference in cancer incidence at the age of 75 years as compared to the screened group, if the incidence increase is primarily due to the carcinogenesis of radiation. Any study design that studies the effect of screening cessation will also help determine the degree to which screening mammography actually causes breast cancer.
The observed incidence of breast cancer (invasive + in situ) has almost doubled in women aged 65-69 years in the United Kingdom between 1996 and 2006, after the NHS breast cancer screening program was implemented for women aged from 50 to 64 years. Similar stable increases are seen in other countries after waiting enough time after implementation of screening. We are facing an epidemic of mammography-induced cancers.
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Re: Cost of extending the NHS breast screening age range in England
Alexandra Barratt suggests that a strong trial design could address the question of overdiagnosis. However, cessation of screening will lead to a decrease in the observed cancer incidence as a consequence of reverse lead time, because cancers are detected in advance during screening. An accurate interpretation of lead time is necessary before trying to evaluate overdiagnosis. When this is done, it is found that overdiagnosis is much less of an explanation of the increased incidence of cancer after national screening was implemented than breast cancer caused by the radiation of screening mammography (1). Thus, the group without screening after the age of 70 years will not show a large difference in cancer incidence at the age of 75 years as compared to the screened group, if the incidence increase is primarily due to the carcinogenesis of radiation. Any study design that studies the effect of screening cessation will also help determine the degree to which screening mammography actually causes breast cancer.
The observed incidence of breast cancer (invasive + in situ) has almost doubled in women aged 65-69 years in the United Kingdom between 1996 and 2006, after the NHS breast cancer screening program was implemented for women aged from 50 to 64 years. Similar stable increases are seen in other countries after waiting enough time after implementation of screening. We are facing an epidemic of mammography-induced cancers.
1) https://www.biorxiv.org/content/10.1101/238527v1
Competing interests: No competing interests