Researchers have developed a tablet that lights up cancerous tumours in a mouse's breast tissue under near-infrared light.

Current screening methods often identify lumps but cannot always pinpoint which ones are cancerous.

In a bid to resolve this uncertainty, researchers from the University of Michigan in the United States created a pill so that only cancerous tumours light up.

The oral tablet contains an imaging agent that selectively binds to cancer cells or blood vessels that are unique to tumours, scientists said.

Once the agent has bound to the cancerous cells, the dye fluoresces under near-infrared light, the researchers added.

When testing the imaging technique in mice, the research team found that fluorescent tumours can be detected 1cm to 2cm deep.

They found that the imaging agent binds specifically to cancer cells with "little" background noise in the image.

The team now plan to formulate the pill for humans. If successful, the new technique could benefit women with "dense" breast tissue whose mammograms are typically more difficult to read, they said.

The findings will be presented to the National Meeting and Exposition of the American Chemical Society.

"There's a lot of controversy right now about when patients should start screening for breast cancer," research lead Dr Greg Thurber said.

"Screening can potentially catch the disease early in some patients, but false positives can lead to unnecessary, aggressive treatments in patients who don't need them. We don't know how to select the right patients to treat. Our work could help change that."

Commenting on the development, Jane Murphy, clinical nurse specialist at Breast Cancer Care, said: "These findings have exciting potential - this new pill could improve the speed and accuracy of a breast cancer diagnosis and move screening techniques forward in leaps and bounds.

"It's estimated for every life saved through screening, three women will have unnecessary, often gruelling treatment. So having the ability to differentiate between aggressive and slow-growing tumours means some women could avoid difficult treatment they might not need.

"However, it is very early days for this avenue of research. Until these findings are explored in human trials changes to clinical practice are a distant prospect."