High-tech glasses that may help surgeons to visualise cancer cells have been developed by scientists, said a report.

Cancer cells are notoriously difficult to see, even under high-powered magnification, US researchers said in the Times of India report.

Surgeons will be able to distinguish cancer cells from healthy cells, helping to ensure that no stray tumour cells are left behind during surgery.

"We're in the early stages of this technology, and more development and testing will be done, but we're certainly encouraged by the potential benefits to patients," breast surgeon Julie Margenthaler, an associate professor of surgery at Washington University was quoted as saying.

The current standard of care requires surgeons to remove the tumour and some neighbouring tissue that may or may not include cancer cells, researchers said.

The samples are sent to a pathology lab and viewed under a microscope. If cancer cells are found in neighbouring tissue, a second surgery often is recommended to remove additional tissue that also is checked for the presence of cancer.

The glasses could reduce the need for additional surgical procedures and subsequent stress on patients, as well as time and expense.

Margenthaler said about 20 to 25 per cent of breast cancer patients who have lumps removed require a second surgery because current technology does not adequately show the extent of the disease during the first operation.

The technology, developed by a team led by Samuel Achilefu, professor of radiology and biomedical engineering at Washington University, incorporates custom video technology, a head-mounted display and a targeted molecular agent that attaches to cancer cells, making them glow when viewed with the glasses.

Researchers noted that tumours as small as one mm in diameter could be detected.

In pilot studies conducted on lab mice, the researchers utilised indocyanine green, a commonly used contrast agent approved by the US Food and Drug Administration.

When the agent is injected into the tumour, the cancerous cells glow when viewed with the glasses and a special light, said the report.