Investigating Breast Lumps
- Fine-needle Biopsy
The doctor is able to obtain a small quantity of cells (biopsy) from the breast lump by inserting a thin (or fine) needle attached to a syringe. Inserting a needle in the breast causes mild discomfort, similar to that experienced when having a blood test, and occasionally causes slight bruising of the breast that fades away in a few days. This test is also called fine needle aspiration cytology and the procedure is shown in Figure 4.
The cells obtained from the biopsy are stained with special dyes and then looked at under the microscope by a specialist, called a cytologist. The cytologist will decide whether the cells have any abnormal features that may indicate that they are cancerous. In practice, the cells are assessed (or graded) from C1 to C5 (Table 5).
The accuracy of this test depends upon the breast specialist obtaining a sample from the lump, and upon the cytologist accurately grading the cells under the microscope. If the test is positive (i.e. grade C5) then it is almost certain (99.5%) that the lump is a cancer. However, a negative test (i.e. grade C2) does not exclude the possibility of cancer but merely makes the diagnosis of cancer less likely. If the needle biopsy result is graded C1, it usually implies the sample was inadequate for analysis and the test should be repeated.