Cytogenetic studies in 32 patients with myelodysplastic syndrome: insights to specific chromosomal abnormalities and prognosis.

Cytogenetic studies were performed on a group of 32 patients with myelodysplastic syndrome (MDS). Five patients had refractory anemia (RA), four RA with ring sideroblasts (RARS), nine RA with excess blasts (RAEB), eight RAEB 'in transformation' (RAEB-T), three chronic myelomonocytic leukemia (CMML) and three secondary MDS (SMDS). Two patients in the SMDS group had been treated with alkylating agents for lung cancer and polycythemia vera, respectively. The other had been exposed to thorotrast. Chromosome analyses were performed with Q and G bandings on bone marrow cells incubated for 24 hr. A clonal chromosomal abnormality was observed in the marrow cells from 19 of the 32 patients (59%). Chromosomal abnormalities of nos. 5 and/or 7 were found in five patients, and were probably specific for RAEB-T and SMDS. Among the twelve patients with solely abnormal metaphases (AA), eight (67%) progressed to acute leukemia, a higher proportion than the three from the 13 patients (23%) with solely normal metaphases (NN) (P less than 0.05). One of the seven patients (14%) with both normal and abnormal metaphases (AN) developed acute leukemia (AA v. AN, P less than 0.03). In only two of the 12 patients who progressed to acute leukemia (17%), was complete remission achieved. The median survival time was only 4.0 months for patients with karyotype AA compared with 18.0 months for AN and 24.0 months for NN (AA v. AN, P less than 0.05, AA v. NN, P less than 0.05). The absence of cytogenetically normal cells indicated a poor prognosis with frequent progression to acute leukemia which is resistant to chemotherapy. Progression to acute leukemia depended not only on chromosomal abnormalities but also on morphological subtype classified according to French-American-British co-operative group criteria. Morphological findings and karyotype combined gave a good indication of the outcome for patients with MDS.