Diagnostic and prognostic value of chromosome studies in cancer.

Chromosome studies may be of value in determining the diagnosis or prognosis in leukemia and related states. They are rarely helpful with solid neoplasms. Special technical problems associated with such investigations in tumor material must be appreciated. In cases where the diagnosis of acute leukemia is in doubt, demonstration of a chromosome change in the immature cells of blood or marrow is strong evidence of neoplasia; however, the absence of a cytogenetic abnormality does not rule out the diagnosis. The Philadelphia chromosome (Ph) is present in nearly every typical case of chronic granulocytic leukemia (CGL) and may confirm the diagnosis. Absence of the Ph chromosome in CGL or the appearance of additional cytogenetic changes in the neoplastic cells are indications of a poor prognosis. In "preleukemic" myeloproliferative disorders (except polycythemia vera) or unexplained pancytopenia, a clone of chromosomally abnormal marrow cells commonly indicates that clinical leukemia will soon become manifest; conversely, normal marrow chromosomes in these states are often correlated with a prolonged indolent course.