CAN MOLECULAR MARKERS NOW BE USED FOR EARLY DIAGNOSIS OF MALIGNANCY

Most of the presently available cancer markers are neither specific fo r malignancy nor allow early diagnosis. However, the recent elucidatio n of the molecular events occurring during tumorigenesis may provide n ew markers that are likely to be both specific for cancer and sensitiv e for early disease. The key molecules undergoing alterations during c arcinogenesis are the cellular oncogenes and suppressor genes. Alterat ions in these genes can be detected in cells shed from malignant and p remalignant lesions. Thus, mutant p53 genes have been found in urine f rom patients with bladder cancer, mutant ras genes in stools from pati ents with colorectal and pancreatic cancers, and both mutant p53 and r as genes in sputum from patients with lung cancer. These findings show that the genetic alterations in cancer can be detected in fluids or s ecretions that had contact with the malignant tissue, The preliminary studies, however, had small numbers of both patients and controls and used time-consuming, labor-intensive, and expensive assays. For routin e applications, these assays must be simplified, automated, and tested for sensitivity, specificity, and predictive value.