REGIONAL CANCER-CYTOGENETICS - A REPORT ON 1,143 DIAGNOSTIC CASES

The results of studies from a regional cancer cytogenetics diagnostic service are reported. In a 10-year period, 1,143 marrow samples from p atients with newly diagnosed leukemia and myelodysplastic syndrome wer e referred. Successful studies were completed on 992 cases (87%). Amon g all referred cases, the rates of detection of cytogenetically abnorm al clones were 95% for chronic myelogenous leukemia (CML), 54% for acu te lymphoblastic leukemia (ALL), 51% for acute myeloid leukemia (ANLL) , and 43% for myelodysplastic syndrome (MDS). Of 169 cases of CML stud ied 90.5% bore the standard Philadelphia chromosome (Ph), 3.55% had an unusual Ph, and 5.33% were Ph-negative. Among the 59 cases of cytogen etically abnormal MDS, common abnormalities observed were trisomy 8 an d changes resulting in loss of material from the long arm of chromosom es 5 and 7, and 20q-. Of the 168 abnormal ANLL, there was a strikingly non-random pattern of aneuploidy, with monosomy 7 and trisomy 8 predo minating Common structural changes observed were changes resulting in loss of material from the long arm of chromosomes 5 and 7, trisomy 8, rearrangements of 11q23, t(15;17), t(8;21), rearrangements of 12q13 an d 3q, inversion 16, trisomy 11, Ph, trisomy 21, t(6;9) and t(1;22). Th e differences between adult and pediatric findings were minor, with th e exception of chromosome 5 abnormalities, which were common among adu lts with ANLL but rare in the pediatric cases. There were 273 ALLs wit h abnormal cytogenetic findings. There was preferential gain of chromo somes 21, X, 14, 6, 4, 18, 17, and 10 (in decreasing order of frequenc y) in leukemic clones. Of the 193 ALLs with structural changes, many f ell into well-defined categories with established correlations to FAB subtypes. Common changes in ALL cr ere rearrangements of 9p, 12p, 6q, TCR loci, 11q23, Ig loci, and 8q24, and duplication of 1q, Ph, i(17q), t(1;19), i(9q) and dic(9;12). The detailed documentation of the cytog enetic findings in this relatively large, single-institution study wil l likely facilitate the further characterization of rare, primary cyto genetic changes associated with leukemias and MDS. From a managed heal th care perspective, regional cancer cytogenetic services may be cost- effective alternatives to single-institution laboratories. (C) Elsevie r Science Inc., 1997.