Fine needle aspiration
A fine needle aspiration can be done in your specialist's rooms, a hospital outpatient department, or at a laboratory by a pathologist. A very narrow needle is used to take some cells from the lump. These cells are then sent to a laboratory for examination.
A fine needle aspiration may cause a little discomfort but isn't usually any more painful than a blood test. Results from this test may be available immediately or may take some time, depending on where it is done.
Sometimes a biopsy will be necessary. A biopsy is the removal of a sample of a lump or the entire lump for examination under a microscope.
A larger needle than that used for fine needle aspiration is used to obtain a sliver of tissue from the lump. This is done with a local anaesthetic. A core biopsy can be done by a radiologist under ultrasound guidance or in a mammogram machine (stereotactic core biopsy). Sometimes it's done by palpation (feeling) of the lump by the specialist.
Sometimes, a surgical or open biopsy is necessary to remove the whole lump. This small operation is usually done under general anaesthetic, although occasionally a local anaesthetic is all that's needed. To have an open biopsy, you may need to stay in hospital overnight.
Hook wire biopsy
If the abnormality in the breast can only be detected by the mammogram (your healthcare provider can't feel the lump), a guide wire may be inserted in your breast to mark the area to be removed in the biopsy. This procedure takes place in the radiology department.
The placement of the wire is done under local anaesthetic, and the abnormality is then removed, as in an open biopsy, under general anaesthetic. It's then sent to the laboratory for testing.
If the lump is a cancer, hormone tests will be done using immuno-histochemistry (IHC), on the sample that was removed. These tests show whether the cancer cells have special 'markers' on them called 'hormone receptors' (oestrogen/progesterone). If these markers are present, the cancer is described as 'hormone receptor positive' and the cancer is more likely to respond to hormone treatment if this is needed later.
HER2 is a growth factor protein which tells breast cancer cells to grow. Approximately 1 in 5 females with breast cancer test 'HER2 positive', which means their cancer is more aggressive.
Two tests (IHC and FISH) are available to check HER2. The IHC test is used first and if this is only weakly positive, then the FISH test is used. If tests show you have HER2 positive cancer, this will influence future choices of chemotherapy, hormones, or monoclonal antibodies. A monoclonal antibody drug called trastuzumab (Herceptin®, Herzuma®) targets the growth factor so that breast cancer cells stop growing.