Published in the October 1 issue of the Journal of Clinical Oncology, the study is the first to use such a thin section of archival paraffin-embedded tissue and show that a specific set of molecular characteristics indicates the presence of melanoma in the lymph nodes even among patients whose lymph nodes appear cancer-free using standard techniques. By using a small tissue section, pathologists spare more of the whole specimen, which is needed for additional pathology tests.
"Our findings show that by performing molecular analysis on a very small piece of tissue, we can quickly and accurately identify previously undetectable metastases, and provide a more accurate prognosis for patients," said Dr. Dave S.B. Hoon, director of the Department of Molecular Oncology at the John Wayne Cancer Institute in Santa Monica, California, and senior author of the study. "Providing a more accurate prognosis can inform decisions on when and how to treat patients, and could ultimately improve our ability to care for patients with melanoma."
Dr. Hoon and his team designed a molecular test to detect the presence of four melanoma-associated proteins, or "markers," in lymph node tissue. They obtained archived tissue samples from 77 patients. Standard tests revealed that 37 of the samples contained melanoma, indicating a poor prognosis. However, using the new molecular analysis, researchers showed that the lymph nodes of 25 percent of the 40 patients whose nodes were thought to be cancer-free actually contained two or more of the melanoma-associated markers.