Assessment of chromosome 8 copy number in cervical cancer by fluorescent in situ hybridization

Cervical carcinoma is a malignancy which typically occurs at the transformation zone between squamous and glandular epithelium. The vast majority falls into two histologic types, squamous cell and adenocarcinoma. In an effort to identify a subset of cervical cancer characterized by chromosome 8 trisomy, a biomarker extensively explored by this laboratory, we conducted a study of formalin-fixed, paraffin-embedded materials of cervical cancer. A total of 24 cases of cervical cancer were identified from the archives of the Rhode Island Hospital. Fluorescent in situ hybridization (FISH) using a chromosome 8 centromere enumeration probe was conducted to assess the chromosome 8 copy number in these specimens. Hybridization signals were scored among tumor cells in a blinded fashion. Tumors with >/=15% of cells with three signals were scored as trisomic. Of 24 cases studied, 23 were informative. Of the 23 informative cases, 12 (52.2%) were found to be trisomic. Eleven cases (47.8%) were disomic. The frequency of trisomy in a control chromosome 17 probe was 13.0% (3/23). Selected clinicopathologic characteristics of the tumors were also reviewed. The frequency of trisomy 8 among cases of invasive squamous cell carcinoma was 44.4% (8 of 18 tumors) and that of invasive adenocarcinoma was 80% (4 of 5 tumors). The sole tumor which was both trisomic 8 and amplified for the HER-2/neu oncogene was found to be an invasive adenocarcinoma. While the sample size in this pilot study is not large, the data obtained thus far clearly demonstrate that FISH is an appropriate technique for detecting chromosomal trisomies and that a subset of cervical cancer exists that is characterized by chromosome 8 trisomy. Further exploration of this biomarker is warranted.