A chemical-imaging technique may one day allow tracking of prostate cancer without the need for invasive biopsies.

A team led by Sarah Nelson at the University of California, San Francisco, exploited differences in how healthy and cancer cells break down certain chemicals, using them to spot tumours in 31 human patients.

The researchers used magnetic resonance imaging to observe isotopically labelled pyruvate, a compound that supplies energy to cells. Shortly after injecting the labelled pyruvate into patients, researchers could observe it being converted into lactate in prostate tumours, and the conversion sometimes revealed cancer in regions that had been overlooked by conventional imaging. Signals that were more intense indicated faster metabolism of pyruvate, a property that has been linked in animal studies to more-aggressive forms of cancer.

Sci. Transl. Med. 5, 198ra108 (2013)