A new prognostic test can help determine whether a prostate cancer patient will go on to have a recurrence of the disease, even if surrounding lymph nodes initially appear negative for cancer, according to a study by USC researchers.
The test, developed at USC, “appears to be a very powerful test and better than anything else we know of for predicting recurrence,” said Richard Cote, professor of pathology and urology in the Keck School of Medicine of USC. Current trials also are using the test to find hidden metastases in lymph nodes and bone marrow for breast and lung cancers.
The study appears this week in the Journal of Clinical Oncology.
Prostate cancer is the most common non-skin cancer in America, according to the Prostate Cancer Foundation. One in six American men will be diagnosed with prostate cancer, making men 35 percent more likely to be diagnosed with prostate cancer than women are to be diagnosed with breast cancer.
“Thanks to greater awareness as well as increased and improved screening, we see men increasingly diagnosed with prostate cancer in its early stages,” Cote said. “Most of these patients will do very well and will not require treatment beyond surgery or radiation therapy to cure their disease.”
But a proportion of these patients have metastases of the prostate cancer appear later, even when the lymph nodes removed at the time of the cancer surgery appeared negative for cancer, he said.
Cote and his colleagues looked at 3,914 lymph nodes from 180 patients who were staged as having lymph nodes negative for cancer based on standardized histologic evaluation (visual scan under a microscope). The lymph nodes were then evaluated for occult (hidden) metastases using new specific immunohistochemistry tests that can detect cancer on a cell-by-cell level.
Their new analysis checks for cells that react with antibodies to cytokeratins and PSA. The team’s testing found occult tumor cells in the lymph nodes of 24 of the patients whose lymph nodes previously had been diagnosed as cancer-free.
The test used to detect the occult tumor cells is more sensitive than any clinical, pathologic or radiographic techniques, Cote said.
The group then compared cancer recurrence and survival in those patients with the hidden tumor cells versus those without the cells. The presence of occult tumor cells was associated with increased prostate cancer recurrence and decreased survival. In fact, “the outcome for patients with occult tumor cells was similar to those who were identified as having positive lymph nodes at the time of the surgery,” Cote said.
“We have shown that occult tumor spread in lymph nodes is a significant predictor of disease recurrence,” he said.
Work was supported by grants from the National Institutes of Health, the National Cancer Institute, the Department of Defense and the California Cancer Research Program.