Making tumors glow to improve cancer

Photo courtesy of the University of Pennsylvania

CANCER DIGEST – July 29, 2014 – Between 20 and 50 percent of cancer patients who undergo surgery end up with recurrence of their cancer, indicating that the surgeon missed some of the diseased tissue from the site. Identifying the edges of a tumor can be difficult to do during a procedure, and typically surgeons have to rely on visual examination of the tumor and feeling for differences with their fingers.

A group of researchers at the University of Pennsylvania is experimenting with new strategies using an injectable dye that accumulates in cancer tissues much more than normal tissues. The dye, called ICG, has been around a long time. What’s new is they are using it under near infrared light. They published results of a small clinical trial involving 5 patients in the journal PLOS ONE.

Five patients with cancer in their lungs received an injection of ICG prior to surgery. During the procedure, surgeons removed the tumors, which were then inspected using NIR imaging and biopsied. In four of the patients, the surgeon could easily tell tumor from non-tumor by sight and by feel. In a fifth patient, however, even though a CT and PET scan indicated that the tumor was a solitary mass, NIR imaging revealed glowing areas in what were thought to be healthy parts of the lung.

One drawback of the technique is that ICG is also absorbed by inflamed tissue making it difficult to tell inflamed tissue around the tumor from the tumor. The Penn researchers are working to identify an alternative targeted contrast agent that is specific to a tumor cell marker to avoid this problem.