Medical view:There are important differences between breast cancer screening and assessing a breast lump, Dr Muiris Houstonwrites
While it is clear that the system of care for women with symptomatic breast disease in Portlaoise fell below acceptable standards, a number of misunderstandings concerning best practice have emerged in recent days.
It is important to distinguish between best practice in the screening of women with no symptoms of breast disease (as occurs in BreastCheck) and the assessment of women who have found a breast lump.
BreastCheck is based on an X-ray of the breast called a mammogram. Carried out by a skilled radiographer, the resulting images are separately read by two consultant radiologists with specialist training in breast disease.
This is called double reading and is the minimum acceptable practice in a population-based screening programme.
Women with a breast lump, who are naturally concerned they might have breast cancer, are looked at differently. A self-selected group by virtue of their symptoms, mammography alone is not sufficient to distinguish between a benign and malignant lump.
This is where triple assessment is important. Contrary to what the Taoiseach told the Dáil yesterday, triple assessment is used to assess whether a woman with a suspicious symptom has got cancer or not.
So a woman with a breast lump needs to be clinically examined by both a radiologist and a surgeon, and to have a mammogram or breast ultrasound (or in some cases both) performed. Either clinician may take a biopsy of the lump, which is then sent for analysis to a pathologist with breast expertise. Therefore, the woman is assessed using the expertise of three separate specialists - hence the term triple assessment.
The radiological assessment of a woman with a breast lump does not require the double reading of a mammogram. The report of the National Quality Assurance Group for Symptomatic Breast Services stipulates that consultant radiologists must report at least 1,000 mammograms per year, but there is no reference to a double-reading requirement.
Instead, the triple assessment process concludes with a multidisciplinary meeting at which doctors and others from the three specialist disciplines discuss their findings. In fact, an even more rigorous process than double reading takes place, because all findings (X-ray, biopsy and clinical examination) are discussed at length by all members of the team before a final decision is made.
Utilising triple assessment by a multi-disciplinary team in a specialist breast unit minimises the risk of misdiagnosis.But even with the best system and best experts a small risk of misdiagnosis remains. No medical test - whether a blood test, X-ray or a biopsy - is 100 per cent accurate. A person with a false positive result does not have the disease even though the test suggests they do. This means they are likely to undergo further investigations that are unnecessary.
False negative results occur in people who have the disease, but the test suggest they are disease-free. This is what happened to some of the women assessed in Portlaoise. It was not the failure to double-read mammograms that let these women down; rather it was the absence of the resources needed for quality triple assessment.
The important public health message to emerge from this sorry episode is: if you develop symptoms of breast disease, insist on being seen in a specialist breast unit offering multidisciplinary assessment.
Women concerned about their breast health or a diagnosis of breast cancer can contact the Action Breast Cancer Helpline at 1800 30 90 40.