Is a biopsy necessary to make an accurate diagnosis?
To confirm the diagnosis of cancer in the breast, removal of a specimen from the lesion is required. This was previously often done by an open biopsy in theatre, but these days can be accomplished by fine needle aspiration or a needle core biopsy.
What are the different types of biopsies?
Fine needle aspiration (FNA) uses a very thin needle to collect fluid or cells directly from the mass. Usually, the practitioner can perform this procedure while feeling the lump to help guide the needle. If a mass was seen on a mammogram, but the lump cannot be felt easily, in a specialised breast health centre, a doctor may use ultrasound or computer-guided imaging to help locate the mass and guide the position of the needle. The use of computer-guided imaging to locate the mass and help guide the position of the needle is called stereotactic needle biopsy.
If this procedure locates fluid, it is an indication that the lump is a cyst. If the procedure locates a solid mass, individual cells from the mass will be removed and sent to a laboratory for further analysis under the microscope.
Using FNA, mammography and a clinical breast exam, a practitioner can determine with about 98% accuracy whether a lump is benign or malignant. If, however, there is still doubt, a core needle biopsy may be ordered. No anesthesia is required for FNA. It is used mainly for cystic masses.
Core needle biopsy removes a 3mm by 2cm core of tissue from the lesion. Ultrasound or stereotactic guidance may be used. Due to the size of the needle, local anesthesia is required.
Core needle biopsy is used mainly for assessment of micro-calcifications (tiny calcium deposits that show up as fine white specks on a mammogram). If an experienced team finds micro-calcifications to be suspicious, the final diagnosis of cancer will be made in three to four out of 10 cases.
Incisional biopsy involves surgical removal of just a portion of the mass, which is sent to a laboratory for further analysis under the microscope.
Excisional biopsy involves surgical removal of the entire mass, which is sent to a laboratory for further analysis under the microscope.
Both incisional and excisional biopsies are used only if FNA or core needle biopsy have failed to deliver a diagnosis and there is still a great suspicion that the mass is malignant or if they are not possible due to technical reasons, eg if the mass is directly located next to a prosthesis. These cases are rare exceptions. In the vast majority of cases in a specialised breast centre, the diagnosis will be established without taking the patient to theatre.