Laparoscopy with LEDs Improves Pancreatic Cancer Detection

A laparoscopic technique that uses fluorescent light to improve pancreatic cancer staging and treatment is in development. The approach shows promise over conventional laparoscopy with no evidence of side effects.

More than 80 percent of people with pancreatic cancer are diagnosed after the cancer has metastasized, and by then the prognosis for long-term survival is dismal. Technology visionary Steve Jobs recently died of a rare form of the disease.

A standard xenon laparoscope and a laparoscope using an LED source were compared by researchers and surgeons at the University of California.

Surgeons took two antibodies that are commonly expressed by pancreatic cancer and tagged them with a fluorescent marker, thus making the cancerous tumors "light up" in colors of bright green or red, reported Dr. Michael Bouvet and Dr. Robert M. Hoffman.

The researchers then administered fluorescent antibodies into 6-week-old female mice. With the LED light, they were able to see primary and metastatic tumors more vividly — at a sensitivity rate of 96 percent compared to 40 percent with traditional laparoscopy.

Moreover, fluorescent laparoscopy rendered fewer false positives than traditional laparoscopy, and the researchers could clearly see the surrounding anatomy in the abdominal cavity of the mice. Fluorescent laparoscopy was also sensitive enough to illuminate metastatic lesions smaller than 1 mm, a size that is not visible with a standard laparoscope.

"Laparoscopy is used for staging in patients with cancer, often before we make a big incision," Bouvet said. "Now we've made it even better with the LED light source. We modified it so you can see both the normal background of the anatomy plus the fluorescent tumor signal at the same time.”

Bouvet added that, using 3-mm laparoscopes, they were able to perform LED fluorescence laparoscopy in mice.

The fluorescent marker did not show evidence of toxicity or side effects in the mice. The combination of LED light and fluorescent markers for malignant tumors could potentially sharpen how surgeons detect and treat pancreatic cancer in human patients. If patients have received the fluorescent antibodies before an operation, the surgeon can insert the LED laparoscope through a small incision and determine whether the cancer has metastasized to other areas of the abdomen.

"If it has spread, then we can biopsy those areas and better determine if the best initial treatment should be chemotherapy and save the patient the large incision," Bouvet said.

"If there's no or limited metastases, then we can more completely remove the primary and metastatic tumors because we can see the edges better. We're hoping for a lower rate of local recurrence."

Once the cancerous tumors are illuminated, Bouvet explains, the surgeons can more precisely remove the tumor and any surrounding malignant tissue without injuring the aorta or other blood vessels nearby.

Another potential application for this technique could involve medically treating pancreatic cancer:

"You could tag a specific drug or isotope to target tumor cells. Since the fluorescent antibodies bind specifically to cancer cells, you could deliver certain payloads of drugs that would kill the cancer cells more effectively," Bouvet said.

The technique could also be applied to staging and treating colon cancer, which often is expressed through the same antibodies as pancreatic cancer and treated with the same laparoscopic technology.

Bouvet plans to work with OncoFluor Inc., a biotech company that develops fluorescent compounds for malignant tumors, on securing FDA approval for clinical trials of the fluorescent antibodies in humans.

The researchers’ findings were presented Monday at the 2011 Clinical Congress of the American College of Surgeons in San Francisco.

For more information, visit: www.ucsd.edu