A technique that uses minute fluorescent particles could light the way for surgeons to see and remove even tiny peritoneal mesothelioma tumors, potentially improving the odds of survival.
In a study published in the American Chemical Society journal Nano, researchers with Boston University and Brigham and Women’s Hospital loaded fluorescent rhodamine into microscopic expansile nanoprobes (eNPs), tiny particles designed to expand and release their contents in the presence of cancer.
The theory is that when these nanoprobes are injected into a cancer patient and then exposed to a certain wavelength of light, they will illuminate any tumors they have found, making them much easier for the surgeon to thoroughly remove.
The team reports that the technique was successfully tested in rats with pancreatic tumors that had spread to the peritoneum. The finding is significant for mesothelioma patients because how completely primary and metastatic mesothelioma tumors are removed (as measured by the Completeness of Cytoreduction Score) has a direct impact on mesothelioma prognosis.
Improved Visualization of Mesothelioma Tumors
As with any surgery, completeness depends largely on the surgeon’s ability to clearly see all of the cancer to be removed, including even the very smallest tumors and cancerous cells along the margins of the resection site.
The Boston researchers say delivering fluorescent rhodamine to the site of a tumor like peritoneal mesothelioma by administering eNPs directly into the peritoneal cavity can make even tiny tumors more visible compared to other techniques.
“The covalent incorporation of rhodamine into ~30 nm eNPs increases the fluorescent signal compared to free rhodamine thereby affording a brighter and more effective probe than would be achieved by a single rhodamine molecule,” writes lead author Aaron Colby of the Biomedical Engineering Department at Boston University.
These highly-fluorescent rhodamine-labeled eNPs were found to be 95 percent accurate at identifying and illuminating even minute, sub-mm malignant mesothelioma tumors.
Cytoreductive Surgery for Mesothelioma
Cytoreductive surgery is the only surgical option for people with peritoneal mesothelioma. It was developed in the 1980s and is used to help cure early stage mesothelioma or reduce symptoms like abdominal pain and appetite loss in late-stage mesothelioma patients.
A number of studies have suggested that, especially in combination with heated intraperitoneal chemotherapy (HIPEC), cytoreductive surgery can significantly boost peritoneal mesothelioma survival. One study of cytoreductive surgery and HIPEC for peritoneal mesothelioma produced a median survival of more than seven years.
Colby, Aaron, et al, “Highly Specific and Sensitive Fluorescent Nanoprobes for image-Guided Resection of Sub-Millimeter Peritoneal Tumors”, January 18, 2017, ACS Nano, Epub ahead of print