The test, developed at USC, "appears to be a very powerful test and better than anything else we know of for predicting recurrence," says Richard Cote, professor of pathology and urology at the Keck School of Medicine of USC. Current trials are also using the test to find hidden metastases in lymph nodes and bone marrow for breast and lung cancers.
The study, "Detection of Occult Lymph Node Metastases in Patients with Local Advanced (pT3) Node-Negative Prostate Cancer" 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 says. "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 says.
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 had been previously 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 says.
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 says.
"We have shown that occult tumor spread in lymph nodes is a significant predictor of disease recurrence," he says. "Once surgery is performed, the primary form of treatment is adjuvant systemic therapy. In patients with no evidence of metastasis, success of such therapy is assumed to be due to killing of occult tumor before it becomes clinically evident. Therefore, the ability to detect occult metastasis is pivotal to identification of patients who would most benefit from systemic therapy and also identify patients who may be spared from unnecessary therapy."
Vincenzo Pagliarulo, Debra Hawkes, Frank Brands, Susan Groshen, Jie Cai, John P. Stein, Gary Lieskovsky, Donald G. Skinner, Richard J. Cote, "Detection of Occult Lymph Node Metastases in Patients with Locally Advanced (pT3) Node Negative Prostate Cancer," Journal of Clinical Oncology, 24: 2735-2741, 2006.
Journal
Journal of Clinical Oncology