The chromosomes and causation of human cancer and leukemia: XXXVIII. Cytogenetic experience in Ph1-negative chronic myelocytic leukemia (CML).

Among 300 patients with chronic myelocytic leukemia (CML) followed at our institute during the last ten years, 36 (12%) were thought to have Ph1-negative CML. In eight of these patients, chromosomal abnormalities were found in the leukemic cells; in four, the karyotypic abnormalities were established with banding techniques. The data of the present study and a review of the literature regarding chromosomal changes in Ph1-negative CML indicate that: 1) no characteristic or consistent karyotypic change is present in Ph1-negative CML and that diploidy is more common in this than any other leukemia; 2) the most common changes involve group C chromosomes (particularly +8); and 3) a missing Y is less common in Ph1-negative CML than in its Ph1-positive counterpart. The karyotypic changes in Ph1-negative CML resemble more those encountered in Ph1-positive CML than in acute myeloblastic leukemia (AML). The much shorter survival of the Ph1-negative CML patients vs that of the Ph1-positive group was again substantiated, and some of the previously reported clinical and laboratory findings unique to Ph1-negative CML were confirmed. On the basis of the cytogenetic findings it is concluded that Ph1-negative CML appears to be an entity unto itself.