Breast Cancer tests and diagnosis
The first steps are to analyse the associated symptoms, obtain all the relevant information about your family history and determine whether you have any risk factors associated with breast cancer. During the appointment the specialist will assess your general health and perform a clinical examination of your breasts and lymph nodes. After the appointment the doctor will assess whether your case needs to be studied further with additional tests.
Different tests are used to establish the diagnosis of breast cancer:
Examination and palpation of the breast. The specialist will perform a meticulous examination of the breasts in order to locate any lumps or suspicious areas, to feel the consistency and size, and to identify any changes in the nipples or skin. They will also examine the axillary lymph nodes and those found just above the collarbone; if they are swollen or harder, then it could be a sign the cancer is spreading. More tests will be carried out if the results of the physical examination suggest the presence of breast cancer.
Mammogram. A mammogram is presently the most effective and easiest test to perform in order to diagnose breast cancer at an early stage. It involves taking an X-ray of the mammary glands.
Magnetic resonance imaging (MRI). MRI is used to accurately delimit the extension of the cancer and to select the most appropriate surgical treatment. It is also of great help when assessing the tumour response to chemotherapy, hormonal therapy or biological agents, whenever these treatments are used prior to radical surgery.
Biopsy. This involves taking a sample of the suspected tumour in order to study the cells under a microscope. The biopsy is performed by puncturing the tumour or suspicious area with a needle.
- Fine-needle aspiration (FNA) biopsy. The cells to be studied and drawn into the needle by the negative pressure or suction created with a syringe.
- Core needle biopsy (CNB). This technique uses a needle with a larger diameter and withdraws a small cylindrical core from the tumour. FNA biopsies reveal more information.
- Open surgical biopsy. A surgeon makes an incision in the breast and then extracts a portion of tissue; this is normally performed in an operating theatre.
Bone scintigraphy. A bone scan helps detect whether a cancer has spread (metastatised) from other parts of the body to the bones. It is a nuclear medicine test; this means the procedure involves the injection of a very small quantity of a radioactive substance called a contrast agent.
All of the imaging tests in this list are painless. Some may require the intravenous administration of a contrast agent or tracer before the test.
How is the presence of a tumour confirmed?
The definitive diagnosis of breast cancer is established by a doctor specialising in anatomical pathology who will analyse various factors in order to identify the tumour and predict the prognosis and response to treatment:
Tumour size. The larger the tumour then the greater the risk of it reappearing (what is known as recurrence).
Histological type. This depends on the type of cells where the tumour originated. Tumours that first develop in the milk ducts (ductal carcinomas) are the most common (80%). Tumours originating in milk-producing cells (lobular carcinoma) occur with the second highest frequency.
Histological grade. The histological grade describes the degree of tumour cell differentiation (maturation). Well differentiated cells (grade I) are the most mature and least aggressive, in contrast to poorly differentiated cells (grade III).
Lymph node involvement. The most important prognostic factor is how many lymph nodes are affected. More lymph node involvement equals a greater risk of recurrence. Therefore, whenever breast cancer is operated on, it is vitally important to analyse the axillary lymph nodes as tumours generally spread to this site before anywhere else. One option used to evaluate lymph node involvement is the sentinel node technique (linkar al apartado) which conserves the majority of the axillary lymph nodes to avoid secondary complications arising from the excision of the complete lymph node basin.
Hormone receptors. A pathologist will analyse whether the tumour cells have receptors for two types of hormone: oestrogens and progesterone. Tumours that feature these receptors respond well to hormonal therapy and consequently have a better prognosis.
HER2 (human epidermal growth factor receptor 2). HER2 is a protein involved in cell growth. It is found in normal cells and the majority of tumours, but 15–20% of breast tumours present high concentrations (overexpression) of HER2 which makes the tumour very aggressive. Tumours with HER2 overexpression are often sensitive to anti-HER2 treatment.
Molecular classification of breast cancer subtype
As increasingly sophisticated techniques are developed, oncologists can analyse the genes of each breast cancer. Such techniques have given rise to a more accurate breast cancer classification system which provides a closer prediction of the risk of recurrence.
The molecular classification establishes four types of breast cancer:
- Luminal A. Subtype with hormone receptors (either estrogen, progesterone or both) positive and HER2 negative.
- Luminal B. Subtype with hormone receptors (either estrogen, progesterone or both) positive and HER2 positive receptors.
- HER 2. Subtype with negative hormone receptors and HER2 positive.
- Basal like. Subtype with negative hormone receptors and HER2 negative (also called triple negative breast cancer).
Luminal breast cancer A is the most common type and tends to have a better prognosis than the other three types. Luminal B breast cancer tends to have a worse prognosis than luminal A, but better prognosis than basal tumors and excess HER2 receptors. The researchers suggest that women diagnosed with Luminal A breast cancer may respond well to a treatment that only includes hormone therapy, while women diagnosed with luminal B breast cancer may respond better to a treatment plan with chemotherapy and hormone therapy.