A new method for diagnosing breast cancer could be more effective than a mammogram, according to research by the University of Michigan.
Scientists there are developing a pill that makes tumours light up when exposed to infrared light, and they have demonstrated that the concept works in mice. The research is described in a study in the journal Molecular Pharmaceutics.
About a third of breast cancer patients treated with surgery or chemotherapy have tumours that are benign or so slow-growing that they would never have become life-threatening, according to a study carried out last year. In other women, dense breast tissue hides the presence of lumps and results in deaths from treatable cancers.
Greg Thurber, who led the research team, said: ‘We overspend $4 billion per year on the diagnosis and treatment of cancers that women would never die from. If we go to molecular imaging, we can see which tumours need to be treated.’
The move could also catch cancers that would have gone undetected. Thurber’s team uses a dye that responds to infrared light to tag a molecule commonly found on tumour cells, in the blood vessels and in inflamed tissue. By providing specific information on the types of molecules on the surface of the tumour, physicians can better distinguish a malignant cancer from one that is benign.
Compared to visible light, infrared light penetrates the body easily – it can get to all depths of the breast without any risk of disrupting DNA and seeding a new tumour. Using a dye delivered orally rather than directly into a vein also improves the safety of screening, as in rare cases patients can have severe reactions to intravenous dyes.
‘To get a molecule absorbed into the bloodstream, it needs to be small and greasy. But an imaging agent needs to be larger and water-soluble. So you need exact opposite properties,” Thurber said. ‘It’s actually based on a failed drug. It binds to the target, but it doesn’t do anything, which makes it perfect for imaging.’
The targeting molecule has already been shown to make it through the stomach and liver unscathed, so it can travel through the bloodstream. The team attached a molecule that fluoresces when it is struck with infrared light to this drug. Then, they gave the drug to mice that had breast cancer, and they saw the tumours light up.