Breast cancer screening
Breast cancer screening programmes exist in several countries. Campaigns for self-examination became less prescriptive with experience as it appears to have no impact on mortality. In the UK, previous advice on regular breast self-examination has been replaced by exhortations to be "breast aware".
X-ray mammography is the most commonly used technical modality, but thermography and ultrasound have also been examined. MRI may have advantages, including usefulness in younger women, greater acceptability and an absence of radiation known to be harmful, but insufficient MRI capacity is available in most places for this to take over.
Many breast screening programmes were introduced on the weight of evidence produced in the 1980s. Improvements in the treatment and management of breast cancer means that the predicted benefit of many screening programmes has fallen below the original projections. Cynics have suggested that the undoubted improvement in mortality with breast cancer owes less to the introduction of screening mammography than to the contemporaneous effect of tamoxifen, and, even, that the net effect of screening with ionising radiation may be negative.
- The maximum effectiveness of screening
Around 90% of breast cancers are detected by the womanNeeds citation, benefits from screening therefore apply only to the remaining 10%, unless considerably more predictive techniques were to become available.
A 2009 Cochrane meta-analysis found that analysis of 3 adequately randomised trials failed to show benefit, although inclusion of other sub-optimally randomised trials showed a modest 15% reduction in mortality at the expense of over-diagnosis and over-treatment of some cancers. Another 2009 analysis of several national screening programmes 7 years pre- and post-screening suggests that as many as 1 in 3 of screen-detected cancers consitute an overdiagnosis, i.e. undetected, the cancer would not have otherwise progressed or shortened life. In a study in Denmark, a screening programme in one region of the country did not appear to reduce mortality compared to the rest of the country. Since then there has been increasing concern around overdiagnosis and long term effects of mammography. While screening is likely to reduce breast cancer mortality it has been estimated for every 2000 women invited for screening throughout 10 years, one will have her life prolonged and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily. A further 200 women will experience psychological distress for many months because of false positive findings.
UK NHS Breast Screening Programme
The recent information leaflets for the programme have been criticised for not including the latest evidence due to the changing epidemiology and issues around overdiagnosis and long term effects of mammography.
The cost of MRI per examination is, in 2006, around 10 times that of x-ray mammography. The younger the patient or the more dense her breasts, and the higher her risk, the more cost-effective this is. The UK NICE guidance attempts to relate provision to absolute risk levels, although these differ according to category. Presence of specific genes (principally BRCA1/2 germline mutations) associated with breast cancer is one of the major factors offered for decision.
- ↑ Thomas DB, Gao DL, Ray RM, Wang WW, Allison CJ, Chen FL, et al. Randomized trial of breast self-examination in Shanghai: final results. Journal of the National Cancer Institute 2002;94(19):1445-57.
- ↑ Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane database of systematic reviews (Online). 2009; (4):CD001877.(Epub) (Link to article – subscription may be required.)
- ↑ Jørgensen KJ, Gøtzsche PC. Overdiagnosis in publicly organised mammography screening programmes: systematic review of incidence trends. BMJ (Clinical research ed.). 2009; 339:b2587.(Epub)
- ↑ Jørgensen KJ, Zahl PH, Gøtzsche PC. Breast cancer mortality in organised mammography screening in Denmark: comparative study. BMJ (Clinical research ed.). 2010; 340:c1241.(Epub)
- ↑ Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane database of systematic reviews (Online). 2011; (1):CD001877.(Epub) (Link to article – subscription may be required.)
- ↑ Warner E. Clinical practice. Breast-cancer screening. The New England journal of medicine. 2011 Sep 15; 365(11):1025-32.(Link to article – subscription may be required.)
- ↑ Gøtzsche PC, Jørgensen KJ. The Breast Screening Programme and misinforming the public. Journal of the Royal Society of Medicine. 2011 Sep; 104(9):361-9.(Link to article – subscription may be required.)