Correlation between cytogenetic abnormalities and disease characteristics in multiple myeloma: monosomy of chromosome 13 and structural abnormalities of 11q are associated with a high percentage of S-phase plasma cells.

Cytogenetic studies in multiple myleoma (MM) are limited by the difficulties in obtaining metaphases that can be investigated and few studies have analyzed the relationship between cytogenetics and clinical disease characteristics. The aim of our study was to analyze the recurrent cytogenetic changes in MM and to correlate them with clinical and biological characteristics including the percentage of S-phase plasma cells (PCs).
Chromosomal abnormalities were analyzed in 86 patients with MM. In all patients, two types of cultures (5 d culture with interleukin-4 and unstimulated 72 h culture) were used for cytogenetic analysis. DNA content analysis (ploidy and cell cycle analysis) together with the most relevant clinical and biological disease features were studied.
Cytogenetic analysis was successful in 72 of the 86 patients (84%). Forty-seven patients (65%) had an abnormal karyotype. The most frequent trisomies involved chromosomes 3, 5, 9, 11, 15, 19, 22, 1, 7, 17, 18, and 21, and monosomies affected chromosomes 13 and 8, while structural changes involved chromosomes 1, 11, 14q32, 4p16 and 16q22-23. Patients with abnormal karyotype displayed a poor performance status, advanced stage, anemia and a high percentage of bone marrow plasma cells. In addition, MM patients with -13/13q- and 11q abnormalities showed a significantly higher proportion of S-phase PCs (p=0.02).
In summary, our study shows a relationship between unfavorable cytogenetics (-13/13q-/11q abnormalities) and a high percentage of S-phase PCs, a well-known adverse prognostic factor.