title: Heterogeneity for allelic loss in human breast cancer.
abstract: BACKGROUND
  Loss of heterozygosity (LOH) at specific chromosomal regions in the tumor cells implicates the presence of tumor suppressor genes. However, it is also possible for an LOH to be randomly acquired and irrelevant to tumor development.
  
  
  OBJECTIVE
  To determine whether a particular LOH in human breast carcinomas represents a loss of tumor suppressor gene or merely a random loss, we analyzed untreated primary breast cancers for LOH.
  
  
  METHODS
  Ninety-eight primary human breast cancers from previously untreated patients were analyzed for LOH at 12 chromosomal regions including five randomly selected regions and seven regions previously reported in other cancer types and/or breast cancers.
  
  
  RESULTS
  The baseline incidence of LOH was five out of 124 tests (4%) using randomly selected probes on chromosomes 1p, 2p, 4p, 11q, and Xq. Incidences of LOH significantly greater than background were seen in the following chromosomal regions: 22q (10 of 26 cases, 38%); 18p (five of 24 cases, 21%); 17p (30 of 59 cases, 51%); 13q (five of 14 cases, 36%); 3p (13 of 28 cases, 46%); and 1q (18 of 70 cases, 26%). In contrast to previous reports, the incidence of LOH was not significantly different from background for 11p15. In all cases, results were the same for metastatic lymph nodes and primary tumors, suggesting that the losses occurred early in the malignant progression. In cases with LOH at more than one locus, the same DNA sample often varied in degree of signal reduction for the missing alleles.
  
  
  CONCLUSIONS
  These observations indicate the presence of both intertumor and intratumor heterogeneity for LOH.
authors.affiliation: Geraldine Brush Cancer Research Institute, California Pacific Medical Center, San Francisco 94115.
authors.forename: L C
authors.initials: LC
authors.lastname: Chen
authors.forename: W
authors.initials: W
authors.lastname: Kurisu
authors.forename: B M
authors.initials: BM
authors.lastname: Ljung
authors.forename: E S
authors.initials: ES
authors.lastname: Goldman
authors.forename: D
authors.initials: D
authors.lastname: Moore
authors.forename: H S
authors.initials: HS
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D002277:Carcinoma / Q000235:genetics; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000235:genetics; D002872:Chromosome Deletion; D015342:DNA Probes; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D016153:Genes, Suppressor; D006801:Humans; D008207:Lymphatic Metastasis; D008875:Middle Aged
chemical_list: D015342:DNA Probes; D004273:DNA, Neoplasm