CHROMOSOME ANALYSIS OF 97 PRIMARY BREAST-CARCINOMAS - IDENTIFICATION OF 8 KARYOTYPIC SUBGROUPS

Chromosome banding analysis of 97 short-term cultured primary breast c arcinomas revealed clonal aberrations in 79 tumors, whereas 18 were ka ryotypically normal. In 34 of the 79 tumors with abnormalities, two to eight clones per case were detected; unrelated clones were present in 27 (34%) cases, whereas only related clones were found in seven. Thes e findings indicate that a substantial proportion of breast carcinomas are of polyclonal origin. Altogether eight abnormalities were repeate dly identified both as sore chromosomal anomalies and as part of more complex karyotypes: the structural rearrangements i(1)(q10), der(1;16) (q10;p10), del(1)(q11-12), del(3)(p12-13p14-21), and del(6)(q21-22) an d the numerical aberrations +7, +18, and +20. At least one of these ch anges was found in 41 (52%) of the karyotypically abnormal tumors. The y identify a minimum number of cytogenetic subgroups in breast cancer and are likely to represent primary chromosome anomalies in this type of neoplasia. Other candidates for such a role are translocations of 3 p12-13 and 4q21 with various partner chromosomes and inversions of chr omosome 7, which also were seen repeatedly. Additional chromosomal abe rrations that give the impression of occurring nonrandomly in breast c arcinomas include structural rearrangements leading to partial monosom ies for 1p, 8p, 11p, 11q, 15p, 17p, 19p, and 19q and losses of one cop y of chromosomes X, 8, 9, 13, 14, 17, and 22. The latter changes were seen consistently only in complex karyotypes, however, and we therefor e interpret them as being secondary anomalies acquired during clonal e volution. (C) 1995 Wiley-Liss, Inc.