Polymerase Chain Reaction Detects Occult Melanoma Cells

Researchers using a sensitive polymerase chain reaction technique to screen for melanoma markers in minute samples of archival lymph tissue have found that many patients classified as free of melanoma metastases by standard procedures actually carried the deadly cancer cells.

Investigators at the John Wayne Cancer Institute (Santa Monica, CA, USA) employed reverse transcriptase polymerase chain reaction (RT-PCR) specific for four melanoma markers to re-evaluate archival tissue samples from 77 patients. Serial sectioning and immunohistochemistry had originally been used to test the samples. The investigators reported in the October 1, 2003, issue of the Journal of Clinical Oncology that they were able to detect melanoma cells in 25% of samples that had been declared cancer-free by the standard technique.

All the patients were observed for almost five years to determine if there was a correlation between the number or type of melanoma and clinical outcomes. The researchers found that patients with two or more of the markers were more than twice as likely to develop a recurrence of melanoma than patients whose lymph nodes showed zero or one marker, and were nearly five times as likely to die as a result of recurrence.

"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 senior author Dr. Dave S.B. Hoon, director of the department of molecular oncology at the John Wayne Cancer Institute. "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.”




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John Wayne Cancer Institute