New breast scan uses light to pinpoint tumours

A new kind of breast scan has been developed that pinpoints malignant tumours using harmless light instead of X-rays.

The technique highlights calcium crystals in breast tissue that are produced by cancerous cells.

Experts believe it could be especially useful for younger women and others who have dense breasts.

Tumours buried in dense breast tissue are often missed by conventional mammography scans.

Using X-rays and the new imaging method together is likely to catch more cancers than mammography alone, say researchers.

The technique employs invisible near-infrared fluorescent light, and a combination of two chemicals that bind to specific calcium salt crystals.

One of the chemicals is bisphosphonate, a drug used to strengthen bone. The other is a “fluorophore” which glows under the scanning light.

When the light is shone through breast tissue, any areas where malignant tumours have formed are illuminated.

Studies have shown that mammograms may miss 10% to 20% of breast cancers, especially if tumours are hidden in dense tissue.

About half of women under the age of 50, and a third of older women, have naturally dense breasts. In these cases, it is often difficult to tell if a lump of tissue is benign or malignant.

The new technique relies on the fact that malignant breast tumours contain high levels of a particular calcium salt called hydroxyapatite. In benign tumours, a different salt, calcium oxalate, predominates.

The scan is able to highlight hydroxyapatite, while ignoring calcium oxalate.

“By homing in on hydroxyapatite, we can target these malignant cells with a high degree of specificity, and that has the potential to improve the patient’s outcome,” said Dr John Frangioni, from Harvard Medical School in the US.

He has conducted laboratory studies showing that the technique works well on large animals similar in size to humans.

Findings from the research were presented today at the annual meeting of the American Chemical Society in Chicago.

Future work will focus on preparing for tests on human patients. It is likely to be a “few years” before the first patient trials take place, say the researchers.