Cytogenetic abnormalities correlate with the plasma cell labeling index and extent of bone marrow involvement in myeloma

Chromosomal abnormalities have biologic and prognostic significance in mult iple myeloma, especially among patients with relapsed disease. Wie report t he relationship between chromosomal abnormalities and known prognostic fact ors such as plasma cell labeling index (PCLI) and bone marrow plasma cell i nvolvement in 75 consecutive patients undergoing autologous stem cell trans plantation for relapsed or refractory myeloma. Thirty of 70 patients (43%) had a chromosomally abnormal clone in their bone marrow, and in most cases the karyotype was complex (>3 abnormalities). Patients with an abnormal clo ne on cytogenetic analysis had a higher PCLI (median, 1.4) than patients wi th a normal karyotype (0.2) (P < 0.001). Bone marrow plasma cell percentage also differed: median 48% versus 20%, respectively (P < 0.001). The PCLI a nd bone marrow plasma cell percentage cor related positively with the perce ntage of abnormal metaphases on conventional cytogenetic analysis: rho 0.60 (P < 0.001) and 0.46 (P < 0.002), respectively. We categorized patients in to those with 20% or more abnormal metaphases, less than 20% abnormal metap hases, and only normal metaphases. The median PCLI values were 3.3, 1.1, an d 0.3, respectively (P < 0.001). The bone marrow plasma cell percentage med ian values were 62%, 40%, and 25%, respectively (P = 0.003). Chromosomal ab normalities may offer a proliferative advantage to the neoplastic plasma ce ll, thereby leading to an unfavorable outcome. (C) Elsevier Science Inc., 1 999. All rights reserved.