Massachusetts General Hospital investigators say a microchip-based device they developed -- called the CTC chip -- can detect and analyze tumor cells in the bloodstream to determine the genetic signature of lung tumors.

"When the device is ready for larger clinical trials, it should give us new options for measuring treatment response, defining prognostic and predictive measures and studying the biology of blood-borne metastasis, which is the primary method by which cancer spreads and becomes lethal," said Dr. Daniel Haber, the study's senior author.

CTCs -- circulating tumor cells -- are living solid-tumor cells found at extremely low levels in the bloodstream. Until the development of the chip it wasn't possible to get information from CTCs that would be useful for clinical decision-making.

The current study was designed to determine whether the device could go beyond detecting CTCs to helping analyze the genetic mutations that can make a tumor sensitive to treatment with targeted therapy drugs.

A pilot study of the device is to appear in the July 24 issue of the New England Journal of Medicine.