The surgeon carefully maneuvered the miniature tools on the surgical robot into position, aiming to remove the tumor in his patient’s kidney. He was experienced and in familiar territory — but now he also hadinnovative new technology to light his way.

City of Hope surgeons recently became the first in California to use a unique visual tool to perform kidney cancer surgery. Only six others worldwide had previously used the method.

The technique, developed by the maker of the da Vinci surgical robots in use at City of Hope, involves a dye called indocyanine green. Physicians infuse the dye into a cancer patient’s blood. From there, it spreads throughout the body. Then, the surgeon shines near-infrared light — light that cannot be seen by the human eye — on the area of the tumor.

Under the special light, the dye makes healthy tissue glow a fluorescent green color. But tumors take up less of the dye than normal tissue does, so they appear dull and gray. The contrast makes it easier to see and remove the tumor while avoiding healthy tissue and blood vessels.

In complex organs like the kidney, this clarity can be crucial; nicking any of the blood vessels could cause significant blood loss.

The light also guides how surgeons restrict blood to the kidney before they can operate. Clamping off the main artery to the kidney would starve it of vital blood and damage the organ. So before starting to remove a kidney tumor, the surgeon turns on the special light. Normal kidney tissue and the blood vessels that feed it suddenly glow bright green, while tumor tissue shows much less color.

“Flipping back and forth from normal light to near-infrared lets us see the blood vessels that feed the kidney, so we can isolate the main one that runs to the tumor,” said surgeon Mark Kawachi, M.D., clinical associate professor of surgery in the Division of Urology and Urologic Oncology. This allows the surgeon to precisely remove the tumor without restricting needed blood flow to the remainder of the kidney.

The U.S. Food and Drug Administration has approved the fluorescence imaging system for kidney surgery, but City of Hope is helping to expand the technique.

Said Kawachi: “We’re looking into using the system in prostate cancer surgery and to improve our ability to see lymph nodes in patients with invasive bladder cancers.”