New research: Fiber optic probes help remove cancerous tissue during surgery

Fiber optic probes can distinguish between cancerous and normal tissue at the edge of the tumor being resected in real time by detecting the difference in pH between the two types of tissue. This may help the surgeon avoid removing too much healthy tissue during surgery and may also avoid leaving any cancerous tissue.

The study was published in the journal Cancer Research by Dr. Schartner, Ph.D., Department of Endocrinology and Surgery Oncology, Royal Adelaide Hospital.

Schartner said: "The current technical problem for surgical resection of cancer is primarily the lack of a reliable method of identifying tissue types during surgery, so surgery relies extensively on the surgeon's experience and judgment to determine how much tissue to remove around the edge of the tumor." Therefore, surgeons typically perform so-called cavity scraping, which can result in the removal of excessive healthy tissue. On the other hand, many patients do not remove the entire tumor during the initial surgery and will require follow-up surgery to remove residual cancer tissue.

He added: "This is very painful for the patient and has been shown to have long-term adverse effects on the patient."

Schartner and the team designed a fiber optic probe that can detect cancer cells during surgery based on the principle that cancer and normal cells have different pH, which is a measure of the acidity or alkalinity (alkalinity) of the substance. Schartner points out that tumor cells are usually more acidic than normal cells.

Schartner explains that when a probe is applied to a tissue, the pH indicator embedded in the polymer layer at the tip of the fiber optic probe changes the color of the light it emits depending on the pH of the region in which it is placed. The probe is connected to a light source that emits fluorescence and can be detected at the other end of the probe using a miniature spectrometer.

The researchers tested specimens of their probes in four mastectomy, one of which detected the transfer of melanoma from the axilla to recurrent breast cancer.

After measuring the edges of these samples multiple times, the researchers found that this pH method was able to distinguish tumors from normal areas with 88% sensitivity and 90% selectivity. Pathological evaluation of these samples was used to determine tumors and normal areas as a reference.

Because of the phenomenon of the cell's own luminescence, the researchers used "lift and measure" techniques to avoid interference with the measurement of autofluorescence. To do this, the probe is first brought into contact with the tissue, but the fluorescence is measured after the probe is lifted from the tissue surface, at which point the probe remains initially measured, but no light emitted from the tissue surface interferes with the tissue.