Frequency of incidental breast cancer and precancerous lesions in autopsy studies: a systematic review and meta-analysis.
December 14, 2017
Yet another study, other than that of Prof. Autier, recently published in the BMJ* (see at the bottom of the article) reinforces the fear that among the women treated after detection of a cancerous lesion through screening, and therefore in absence of symptoms, a certain number (one out of two in the Autier study from the Netherlands) would never have suffered from it during their lifetime; the removal of a breast, unnecessary radiotherapy or tiring chemotherapy could have been avoided for these women.
Elizabeth T. Thomas1 , Chris Del Mar 2 , Paul Glasziou 2 , Gordon Wright 1 , Alexandra Barratt 3 and Katy J. L. Bell 2,3
1 Faculty of Health Sciences and Medicine, Bond University, Robina, QLD 4229, Australia.
2 Centre for Research in Evidence-based Practice, Faculty of Health Sciences and Medicine, Bond University, Robina, QLD 4229, Australia.
3 Sydney School of Public Health, Sydney Medical School, Edward Ford Building (A27), University of Sydney, Fisher Road, Sydney, NSW 2006, Australia
Autopsy studies have demonstrated the frequency of occult cancers in the population, but the evaluations performed by these primary studies involved a small number of deceased patients each time.
The authors included 13 studies from 10 different countries, over 6 decades (from 1948 to 2010), comprising 2363 autopsies with 99 cases of so-called "incidentalomas" (cancers of incidental finding), or precancerous lesions.
When the histological examination was more comprehensive (on more than 20 histological sections), there were more incidentalomas detected, mostly in situ cancers and atypical hyperplasias, but few invasive cancers.
This means that the more histological research is carried out on deceased persons, the more latent cancers are found, with an average frequency of this "accidental" cancer of around 19.5% (0.85% invasive cancer + 8.9% in situ cancer + 9.8% atypical hyperplasia).
Therefore, the more we seek and the more we find, which raises questions about the development of more and more efficient investigative techniques that are going to discover more and more of these lesions abusively. The consequences of the resulting over-treatments are to be considered even more seriously in older women because of the increased susceptibility to adverse effects of treatments in this population.
Systematic review in ten countries over more than six decades has found that incidental discovery of occult, in situ cancers or precancerous lesions is very common in women, in whom breast disease was not known during their lifetime.
It appears that cancerous or pre-cancerous lesions are discovered incidentally in 2 out of 10 women during these autopsies. The authors estimate that 40% of invasive cancers detected by systematic mammography and 24% of all invasive cancers would be over-diagnosed.
This high frequency of undetected cancers, in situ and atypical hyperplasias in these autopsy studies, suggests that screening programs should be more cautious in promoting detection methods with increased sensitivity, thus increasing these unnecessary diagnoses.