A surgical method employing fluorescent imaging agents can help surgeons remove malignant tissue that otherwise might have been missed in women with ovarian cancer.

“Ovarian cancer is notoriously difficult to see, and this technique allowed surgeons to spot a tumor 30 times smaller than the smallest they could detect using standard techniques,” affirmed Philip S. Low of Purdue University in West Lafayette, Indiana, in a statement announcing his group’s findings.

Low, who is the Ralph C. Corley Distinguished Professor of Chemistry at Purdue, is credited with inventing the technology, in which a fluorescent imaging agent is attached to a modified form of folic acid. As Low and his co-investigators noted in their report for Nature Medicine, 90% to 95% of epithelial ovarian cancers overexpress folate receptor-alpha (FR-α), prompting their investigation of a fluorescent agent that targets FR-α.

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The agent/folic acid combination is injected into the patient 2 hours before surgery. During the operation, a special camera system consisting of a multispectral fluorescence camera illuminates the cancer cells and displays their location on a flat-screen monitor.

In a phase 1 clinical trial in the Netherlands that was designed to evaluate the new technology, surgeons could see clusters of cancer cells as small as one-tenth of a millimeter in diameter. Previously, the average minimal cluster size that could be detected by visual or tactile methods was 3 mm in diameter.

Use of tumor-specific intraoperative fluorescence imaging has the potential to improve staging as well as increase the amount of cancerous tissue removed during surgery, thereby improving prognosis.