COLUMBUS, Ohio -- An experimental technique that helps identify colorectal-cancer patients who may best benefit from surgery may also work well on patients with pancreatic cancer, new research shows.
“This technology may help us decide who will benefit from more extensive surgery and who might be spared a major operation,” said Gregory LaValle, assistant professor of surgery and a researcher with Ohio State University's Comprehensive Cancer Center.
The technique helps surgeons determine how far a tumor has spread within the body. Patients whose cancer has spread beyond the site of the tumor often stand a very poor chance of being cured by the treatment. In fact, extensive surgery can do more harm than good in these patients by causing stress and trauma that reduces the patient’s quality of life.
Determining which patients will not benefit from extensive surgery is therefore important.
This study, which was led by LaValle, was published in a recent issue of the journal Surgery. The experimental technique uses an antibody labeled with radioactivity that binds to a protein produced by tumor cells. Patients are given the antibody intravenously a few weeks before surgery.
During surgery, the physician scans the abdomen with a hand-held probe searching for signs of radioactivity. In theory, the detection of radioactivity signals the presence of cancer cells. The technology is thought to be most useful for locating clusters of tumor cells that are too small to be visible in tissues and lymph nodes surrounding the tumor.
Locating these so-called “occult” tumor cells gives a more accurate idea of whether the tumor has spread beyond its site of origin, and, if so, how extensively it has spread. This information is essential for the surgeon to determine the stage of a patient’s cancer.
In general, stage-I cancer means the tumor has not spread beyond the organ in which it originated (i.e., it is localized). In many types of cancer, surgery can often cure these patients. In stage-II cancer, the tumor has invaded neighboring tissue; in stage III, it has spread (or metastasized) to nearby lymph nodes. By stage-IV, the tumor has spread to distant regions of the body.
Many cancers, including pancreatic cancer, are staged during surgery, when the oncologist can inspect the tumor and the surrounding organs and lymph nodes. Suspicious lymph nodes are removed and studied for signs of cancer cells. A hair-thin slice is taken from the node and examined using a microscope. If malignant cells are found, it indicates the tumor has spread.
This study compared staging pancreatic-cancer patients by the traditional inspection method to the results of staging them by inspection plus use of the antibody and hand-held probe.
The traditional method identified a total of 25 organ sites affected by cancer, while use of the probe identified a total of 29 organ sites. When lymph nodes were examined, the traditional method located six affected nodes, whereas use of the probe identified 44 sites.
The results suggested that the antibody and probe method may be better
than the traditional method alone for detecting how far the tumor had spread.
Because the probe had identified so many more nodes than did the traditional
method, the researchers did additional tests on nine nodes to verify that
cancer was being detected in them. The tests further demonstrated the presence
of cancer cells in six of the nine nodes; three did not. The researchers
speculated that, among other things, these nodes may have contained only
a small number of cancer cells and that these cells may have been missed
by the analysis.
“This technique has already proven useful in patients with recurrent colorectal cancer,” said LaValle. “Our results suggest that with more research it might also help people with pancreatic cancer.”
Pancreatic cancer is the fifth leading cause of cancer deaths in the United States. It’s also a particularly deadly form of cancer, said LaValle. “The mortality rate from pancreatic cancer is at least 90 percent five years after diagnosis, whereas the five-year mortality rates from tumors like breast or colon cancer is less than 50 percent.”
The study was funded by the Neoprobe Corporation, which manufactures the antibody and hand-held probe.
Contact: Gregory LaValle, (614) 293-8700
Written by Darrell E. Ward, (614) 292-8456; Ward.25@osu.edu
Journal
Surgery