A number of conditions can lead to traces of calcium forming in the tissues of the breast. Microcalcification is the name given to tiny specks of calcium, less than 1mm in size, which show up as bright white spots against the grey/black background of the mammogram picture.

About 4 out of 10 breast cancers contain clusters of microcalcification. Microcalcification is even more common in the precancerous condition of ductal carcinoma in of the breast (DCIS) where it is seen in about three quarters of all cases.

In mammograms used for screening for breast cancer microcalcification may be the first sign that a cancer is present, with clusters of calcium specks showing up even though there is no lump to feel and no tumour showing on the mammogram film.

Microcalcification does also occur with a number of completely benign, non-cancerous, breast conditions including fibroadenomas and papillomas. Very often the specialists can tell from the shape and pattern of the calcium specks whether or not there is likely to be a cancer present.

If there is any uncertainty as to whether the microcalcification is due to cancer, or precancerous DCIS, then your doctors will almost certainly arrange a biopsy to get a definite answer. This involves taking a tiny piece of breast tissue and is usually done with a needle and a local anaesthetic in an outpatient clinic.