[Gene diagnosis of cancer]

Recently, many DNA alterations have been reported in most of cancers. Now, gene diagnosis of cancers becomes a hot topic. There are at least three kinds of cancer-related genes, oncogenes, tumor suppressor genes and DNA mismatch repair genes. In hereditary tumors, gene diagnosis is particularly important, because it is possible to find predisposing individuals even before the appearance of cancers. Of course, gene diagnosis is also very useful for nonhereditary tumors. A very small numbers of cancer cells in blood, sputum, urine and stool can be detected by the highly sensitive PCR (polymerase chain reaction) technique. Prognosis may also be predicted from specific gene alterations in cancers.