Mice that underwent this type of image-guided surgery survived 40 percent longer than those who had tumors removed without the guided system.
"What's nice about this system is that it allows for real-time information about the size, depth, and distribution of tumors," says Angela Belcher, the James Mason Crafts Professor of Biological Engineering and Materials Science at MIT, a member of the Koch Institute for Integrative Cancer Research, and the recently appointed head of MIT's Department of Biological Engineering.
The researchers are now seeking FDA approval for a phase 1 clinical trial to test the imaging system in human patients. In the future, they hope to adapt the system for monitoring patients at risk for tumor recurrence, and eventually for early diagnosis of ovarian cancer, which is easier to treat if it is caught earlier.
Belcher and Michael Birrer, formerly the director of medical gynecologic oncology at MGH and now the director of the O'Neal Comprehensive Cancer Center at the University of Alabama at Birmingham, are the senior authors of the study.
Belcher and Birrer joined forces to work on this problem through the Bridge Project, a collaboration between the Koch Institute and Dana-Farber/Harvard Cancer Center. Belcher's lab has been developing a novel type of medical imaging based on light in the near-infrared (NIR) spectrum. In a paper published in March, she reported that this imaging system could achieve an unprecedented combination of resolution and penetration-depth in living tissue.
In the new study, Belcher, Birrer, and their colleagues worked with researchers at MIT Lincoln Laboratory to adapt NIR imaging to help surgeons locate tumors during ovarian cancer surgery, by providing continuous, real-time imaging of the abdomen, with tumors highlighted by fluorescence. Previous analyses have shown that survival rates are strongly inversely correlated with the amount of residual tumor mass left behind in the patient during debulking surgery, but many ovarian tumors are so small or hidden that surgeons can't find them.
To make the tumors visible, the researchers designed chemical probes using single-walled carbon nanotubes that emit fluorescent light when illuminated by a laser. They coated these nanotubes with a peptide that binds to SPARC, a protein that is overexpressed by highly invasive ovarian cancer cells. This probe binds to the tumors and makes them fluoresce at NIR wavelengths, allowing surgeons to more easily find them with fluorescence imaging.
The researchers tested the image-guided system in mice that had ovarian tumors implanted in a region of the abdominal cavity known as the intraperitoneal space, and showed that surgeons were able to locate and remove tumors as small as 0.3 millimeters. Ten days after surgery, these mice had no detectable tumors, while mice that had undergone the traditional, non-image-guided surgery, had many residual tumors missed by the surgeon.
By three weeks after the surgery, many of the tumors had grown back in the mice that underwent image-guided surgery, but those mice still had a median survival rate that was 40 percent longer than that of mice that underwent traditional surgery.
No other imaging system would be able to locate tumors that small during a surgical procedure, the researchers say.
The researchers hope to deploy this type of imaging to monitor patients after surgery, and eventually to develop it as a diagnostic tool for screening women at high risk for developing ovarian cancer.
MEDICA-tradefair.com; Source: Massachusetts Institute of Technology
