Illuminating Cancerous Tumors

A new technology using fluorescent peptides can identify cancerous cells, facilitating accurate identification of malignancies during resection and sparing healthy surrounding tissues and lymph nodes.

Developed by a team of surgeons and scientists led by 
Quyen T. Nguyen, M.D., Ph.D., associate professor of head and neck surgery at the University of California, San Diego School of Medicine, radiometric activatable cell-penetrating peptides (RACPPs) were injected into test mice to track cancerous growths.

The fluorescent peptides emit light if another light is shined on them. Using light to amplify fluorescence, surgical oncologists were immediately able to clearly view exactly where the cancer was located. This study was recently published in Cancer Research.

Streamlining Surgery While Improving Outcomes

This approach offers surgeons real-time molecular navigation when treating forms of cancer involving lymph nodes.

“In both breast cancer and melanoma, we do sentinel lymph node mapping — which looks for the first-draining lymph node of the cancer — and then we take that lymph node out and give it to the pathologist,” says Dr. Nguyen. “This is all done while the patient is under anesthesia and the surgeon and anesthesiologist are waiting. The pathologist has to cut the node, look at it and see if there is cancer in it. If there is, the surgeon continues to remove more lymph nodes. If there isn’t, you don’t have to continue. But you can imagine, this is a whole process that can be improved or shortened if the surgeon can tell before cutting out that very first lymph node.”

Other areas of the body affected by cancer, such as the head and neck, do not have a first-draining lymph node, which means surgeons may spend hours removing multiple nodes in search of cancerous cells, only to find most noncancerous in nature.

“The clinical implications for patients are huge,” says Dr. Nguyen. “For patients, you can avoid unnecessary surgery and avoid cancer being left behind. There are significant system-wide cost savings if we can avoid unnecessary surgery. For surgeons, it increases confidence because they have molecular indications confirming their clinical assessments.”

In 2011, Dr. Nguyen completed a similar study with Nobel Prize winner Roger Tslen, Ph.D., professor of pharmacology at University of California, San Diego School of Medicine, using the same technique to identify hidden peripheral nerves. The study was first published in the online journal Nature Biotechnology.

Later this year, researchers will conduct the first RACPP clinical trial, which will be divided into three phases for appropriate oncology patients.

To learn more about this study and its upcoming clinical trials, visit



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