Mammography: Detecting breast cancer

Mammography is an x-ray examination of the breast. There are two types of mammography. Screening mammography detects breast disease in a woman who does not have any symptoms. Diagnostic mammography is used to help make a diagnosis in a woman who has breast complaints such as a lump or an abnormality that was discovered during a screening mammogram.

Calcification in the breast - what does it mean?

Calcifications are tiny deposits of calcium within the breast that appear as white dots on mammograms (see Figure 1). While most calcifications are non-cancerous, some are associated with breast cancer.

Non-cancerous causes of calcifications

There are many non-cancerous causes of calcium in the breast including:

• Fibroadenoma - a non-cancerous growth that degenerates over time leaving behind large, chunky deposits of calcium that can look like popcorn (see Figure 2).
• Scar tissue in the breast - calcium can be deposited in scar tissue after, for instance, a surgical biopsy (removal of a tiny sample of tissue for examination) or a reduction mammoplasty (breast reduction surgery).
• Fluid-filled lumps - calcium can appear with a cyst - a non-cancerous (benign) lump that contains fluid. When a mammogram is taken at a horizontal angle with a patient standing, the calcium may be seen at the bottom of a cyst, causing a slightly curved fine line that can be easily diagnosed (see Figure 3).

Determining whether calcifications are cancerous

A mammogram can often accurately diagnose most calcium deposits as either cancerous or benign. The in-between varieties require additional mammograms, which are sometimes taken at different angles than the standard one, often with magnification.

Sometimes a technique called "spot compression" is used to squeeze only a part of the breast. Although spot compression is more uncomfortable than the full-breast device used for the routine pictures, the slightly greater discomfort is worth the greater detail that becomes visible on the mammogram.

If there is breast cancer, a calcification may occur along with a lump, or on its own which can be due to non-invasive "in situ" cancer. With this type of cancer, the cancer cells are located inside the milk duct - they have not yet invaded through the wall of the duct.

If the radiologist believes that the calcification is highly likely to be non-cancerous, a biopsy (removal of a tiny piece of tissue for examination) is usually not needed. However, follow-up mammograms are often recommended within six months to confirm that cancer is not present. If there is even a small chance that a cancer is present, the radiologist will recommend that some of the calcium be removed and checked by a needle biopsy or surgery.