Gimzewski and Rao use the ultrasharp tip of an atomic-force microscope probe to apply force to single cells and measure the resistance. Cancer cells have less resistance to such poking than normal cells do. Gimzewski and Rao's innovation is to study live cells taken directly from cancer patients, rather than cells grown in the lab.

The UCLA researchers are currently probing lung-fluid samples taken from patients with different types of cancer, including prostate and ovarian, and they will also test cells from primary tumors. Gimzewski says that he and his team will also test how cancer drugs affect cell stiffness. They hope that cell stiffness will help researchers determine how aggressive a patient's cancer is and predict whether it will respond to particular therapies.

Sanford Barsky, chief of pathology at the Ohio State University Medical Center, says that atomic-force microscopy is an "esoteric, high-power technique" that's unlikely to be widely adopted by hospitals. If further research supports Gimzewski and Rao's results, Barsky says, it will be important to find out what molecular changes are associated with cancer cells' structural changes. Detecting particular proteins in a clinical setting, says Barsky, is relatively routine; if the structural changes are caused by alterations in a protein, detecting that protein would be cheaper and easier than using atomic-force microscopy.

But Suresh agrees with Rao that cancer hospitals would adopt atomic-force microscopy if it proves clinically useful. The instruments cost about $60,000--well within the budgets of many hospitals. Gimzewski says that he hopes future clinical instrumentation will incorporate automated atomic-force microscopy with the traditional optical microscopes used by pathologists.