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10.1 Which sub-types of non-invasive and invasive breast cancers are most common and what are their frequencies?
The most common type of non-invasive breast cancer is ductal carcinoma in situ (DCIS). This accounts for 15% of all new breast tumours. The most common type of invasive breast cancer is invasive ductal carcinoma (IDC). Around 80% of invasive breast cancers are of this type.
10.2 Why is it important to identify metastatic carcinoma in the sentinel lymph nodes and how does this influence the future management of the patient?
The sentinel lymph node is the first lymph node to drain the tumour. If this node is negative it is highly unlikely that the other lymph nodes would have metastatic disease. This has revolutionized the treatment of the axilla in women with breast cancer, as now patients with negative sentinel lymph node do not require further axillary surgery.
10.3 What are the hormones that are regularly tested for in breast cancer and which laboratory techniques are used for these tests?
ICC is used to assess whether tumours express oestrogen and progesterone receptors. Nuclear staining is determined using a semi-quantitative method such as the Quick score were intensity of staining and percentage of tumour cells staining is assessed.
10.4 Which are the commonest driver mutations in breast cancer?
BRCA1 and 2mutations are drivers of hereditary breast cancer. Otherwise a diverse set of mutations have been associated with sub-types of invasive breast cancer and their importance is still being determined.
10.5 Why is molecular testing important in some patients with breast cancer and how can it help in the management of their disease?
There are various molecular tests that have been developed, however only Oncotype Dx has been granted NICE approval for use under specific criteria. This test is used for early stage breast cancer to determine the recurrence score and benefits or otherwise of chemotherapy.