The vast majority of published cytogenetic studies of malignancy
have been of leukemias and related hematologic disorders (see Fig. 1),
even though these constitute only about 20% of all cancers. It follows
that most of what is known about the clinical applications of
cytogenetic studies has been derived from hematologic malignancies.
More recently, however, there has been a huge expansion in
knowledge of the recurrent abnormalities in some solid tumors, and
it is clear that in these, just as in the leukemias, cytogenetic abnormalities
can help to define the diagnosis and to indicate clear prognostic
differences. Consequently, cytogenetic studies of some solid
tumors are now also moving out of the research environment and
into routine clinical service.