Cytogenetics in solid tumors: lessons from the Philadelphia Chromosome.

Although presently known as an environmentally-related disease and appears mostly sporadic, cancer is regarded as a genetic disease based on the presence of gene mutation as a consistent factor. The "Philadelphia Chromosome" found consistently among chronic myeloid leukemia (CML) patients was the first significant finding of a chromosomal abnormality specifically related to a particular disease. Starting from this point, cytogenetics as the study of chromosomes has become a valuable tool in the assessment of cancer - as an aid in diagnosis, thus guiding therapy, and as a prognostic marker.