Both chromosome 13 abnormalities by metaphase cytogenetics and deletion of 13q by interphase FISH only are prognostically relevant in multiple myeloma.
OBJECTIVE
Deletion of chromosome 13q [del(13q)] has emerged as a major adverse prognostic factor in multiple myeloma (MM). Del(13q) is detected two to three times more frequently by interphase fluorescence in situ hybridization (FISH) than by metaphase cytogenetics (CG). However, it has remained unclear whether or not del(13q) detected by FISH only provides the same prognostic information as its detection by CG.


METHODS
We investigated the outcome of 118 consecutive patients with newly diagnosed MM who were studied by both CG and FISH (RB-1 and/or D13S319 probes).


RESULTS
CG revealed informative MM karyotypes in 35 patients (29.7%), with monosomy 13/del(13q) in 16 of them. FISH was indicative for a del(13q) in 43 patients (36.4%). A del(13q) by FISH was present in all 16 patients with monosomy 13/del(13q) by CG and also in four of 19 patients with informative karyotypes and diploid chromosome 13. Furthermore, del(13q) was present by FISH in 23 of 84 patients with diploid/non-informative metaphases by CG. Overall survival of patients with monosomy 13/del(13q) by CG and of patients with del(13q) by FISH only was not significantly different (median, 35.2 months vs. 33.2 months, P = 0.58). In contrast, patients with diploid chromosome 13 by either technique experienced prolonged survival (median, 65.6 months). Presence of abnormal karyotypes was significantly associated with an increased Ki67 growth fraction.


CONCLUSIONS
FISH of chromosome 13q adds prognostic information to that provided by CG. It is suggested to use FISH analysis in clinical trials if risk stratifications take into consideration the chromosome 13q status.
Kaufmann
Hannes
H
Department of Medicine I, Clinical Division of Oncology and Division of Hematology, University Hospital Vienna, Austria.
Krömer
Elisabeth
E
Nösslinger
Thomas
T
Weltermann
Ansgar
A
Ackermann
Jutta
J
Reisner
Regina
R
Bernhart
Marianne
M
Drach
Johannes
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001854:Bone Marrow Cells / Q000648:ultrastructure; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D002882:Chromosomes, Human, Pair 13; D020732:Cytogenetic Analysis; D005260:Female; D017353:Gene Deletion; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007399:Interphase; D007621:Karyotyping; D008297:Male; D008677:Metaphase; D008875:Middle Aged; D009101:Multiple Myeloma / Q000235:genetics*; D011379:Prognosis