To date, biopsies are the standard for diagnosing cancer. However, they provide only a snapshot in time of the tumor's growth. Now for the first time, scientists from MIT have developed an implantable device that was used to successfully track a tumor marker in mice for a period of one month. The hope is that one day, such a device could provide invaluable minute-by-minute information on whether a tumor is growing or shrinking, how well it may be responding to treatment and whether it is about to metastasize. It may also be used to monitor chemotherapy agents, enabling doctors to determine whether cancer drugs are adequately reaching the tumors. In addition, the device may also be designed to measure pH (acidity) or oxygen levels, which reveal tumor metabolism and how well or poorly the tumor is reacting to therapy.

"What this does is basically take the lab and put it in the patient," says Michael Cima, professor of materials science and engineering at MIT and investigator at the David H. Koch Institute for Integrative Cancer Research at MIT. "With current tools for detecting whether a tumor has spread, such as biopsy, by the time you have test results it's too late to prevent metastasis," notes Cima. "This is one of the tools we're going to need if we're going to turn cancer from a death sentence into a manageable disease."

After transplanting human tumors in mice, the researchers employed the implant to track levels of human chorionic gonadotropin, a hormone produced by human tumor cells. The cylindrical 5-millimeter device is made of polyethylene, a polymer that is commonly used in orthopedic implants. It contains magnetic nanoparticles coated with antibodies specific to the target molecules. The molecules are able to enter the implant through a semipermeable membrane, while the magnetic nanoparticles are trapped inside. The molecules bind to the particles, causing them to clump together. Magnetic resonance imaging is used to detect the "clumping."

The research, which was funded by the National Cancer Institute Centers of Cancer Nanotechnology Excellence and the National Science Foundation, was published online in the journal Biosensors & Bioelectronics this past April. As Cima notes, an implant to test for pH levels may be commercially available within a few years, with devices to test for complex chemicals such as hormones and drugs to follow.

News Release:  New implantable device could track tumor's growth www.virtualmedicalcentre.com  May 31, 2009