UTILIZATION OF POLYMERASE-CHAIN-REACTION TECHNOLOGY IN THE DETECTION OF SOLID TUMORS

BACKGROUND. Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic le sions. Generally, for a positive result, these detection assays requir e that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods fo r detecting a small number of cancer cells. Over the past few years, n umerous clinical studies have used PCR techniques to detect physical a lterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression o f genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of so lid tumors is reviewed. METHODS. A review of the literature on the cli nical utility of PCR and RT-PCR in the detection of solid tumor microm etastasis was conducted. RESULTS. Amplification by PCR is a highly sen sitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approx imately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-bas ed assays have been used to detect cancer cells in biopsies of solid t issue, lymph nodes, bone marrow, peripheral blood, and other body flui ds. Several studies have reported a high specificity and sensitivity o f tumor marker detection and a high correlation between PCR results an d the presence of metastatic disease. However, in a few studies, PCR a ssays have not consistently demonstrated a higher sensitivity and spec ificity of detection than traditional modalities for many types of can cer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies. CONCLUSIONS. PCR ca n detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Repor ts from various study groups have lacked uniformity in their protocols , and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patien ts remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve a s a useful adjunct to clinical decision-making in the future. (C) 1998 American Cancer Society.