Interphase cytogenetics using fluorescence in situ hybridization: an overview of its application to diffuse and solid tissue

The UroVysion fluorescence in situ hybridization assay is an effective tool for monitoring recurrence of bladder cancer

The newly developed UroVysion fluorescence in situ hybridization (FISH) probe was applied to urine specimens from 19 patients being monitored for recurrence of bladder cancer. The results for the multi-target DNA FISH assay were compared with independent analyses of urine cytology and flexible cystoscopy. Patients with tumors identified through the cystoscopy exam were biopsied and/or underwent surgery. In 12 patients with normal cytoscopy, cytology and FISH were also normal. Therefore, the specificity of these two tests was 100%. In 7 patients, a tumor was diagnosed by cystoscopy, and 3 of them had abnormal urine cytology while 6 of them had an abnormal result in the FISH assay. Accordingly, the sensitivity was 43% for the cytology and 87% for the FISH test. Interestingly, a pT1G3 tumor in a bladder diverticulum was not detected by cytology or the FISH test. These results agreed with a large series previously published using similar FISH probes and support the proposal for a multicenter trial to confirm the usefulness of the UroVysion probe as a screening tool to select patients for cystoscopy.

Chromosomal aneuploidy precedes morphological changes and supports multifocality in head and neck lesions

OBJECTIVE

To identify chromosome changes associated with the transformation of dysplastic lesions and to verify evidence for multifocality in synchronous premalignant lesions associated with head and neck squamous cell carcinoma (HNSCC).

STUDY DESIGN

Chromosomal aneuploidy was evaluated in sections of formalin-fixed, paraffin-embedded tissues from 16 patients with HNSCC, including sites with normal squamous mucosa, dysplasia (low- and high-grade), and invasive tumor.

METHODS

A panel of 6 centromeric probes (chromosomes 1, 3, 7, 8, 9, and 17) was analyzed in dual-color fluorescence in situ hybridization assays, using matched hematoxylin-eosin-stained sections for histologic correlation.

RESULTS

Imbalances for most of the targets tested were found in 20 of 24 invasive carcinoma sites, mainly represented by gain in copy number per cell. However, cell populations with chromosome losses and gains in multimodal patterns were concomitantly observed in a number of tumors, indicating a high degree of chromosome instability. The detection of chromosomal aneuploidy precedes the malignant transformation as indicated by findings of monosomy and trisomy in normal squamous mucosa, and in low-grade and high-grade dysplasia sites. Loss of chromosomes 3 and 17 prevailed in low-grade dysplasias, and gain of chromosomes 7 and 8 were prevalent in high-grade dysplasias. Synchronous low-grade and high-grade dysplastic lesions displayed discordant molecular signatures, suggesting a multifocal origin.

CONCLUSIONS

The interphase fluorescence in-situ hybridization (FISH) assay with centromeric may detect early changes in the progression of dyplastic epithelia to invasive carcinoma and supports the field cancerization theory of multifocality.

Identification of individuals at high risk for head and neck carcinogenesis using chromosome aneuploidy detected by fluorescence in situ hybridization

To visualize the accumulation of chromosome abnormalities in head and neck squamous cell carcinomas (HNSCC) and investigate the extension of the abnormal field, we applied the fluorescence in situ hybridization (FISH) technique to tumor cells and cells collected from a large extension of clinically normal buccal mucosa distant from the tumor in 10 patients. DNA probes specific for 14 human chromosomes (1, 2, 3, 6, 7, 8, 9, 10, 11, 12, 15, 17, X, and Y) were used in dual-target, dual-color FISH assays. Control specimens were collected from oral mucosa of 10 healthy non-smokers, in order to define the tolerance limits for abnormalities, and from 10 healthy smokers. Extensive aneuploidy was detected in most of tumor specimens, more frequently represented by chromosome gains than losses. Interestingly, the clinically normal distant oral regions displayed chromosomal aneuploidies in seven out of the 10 patients tested. These findings support the occurrence of field cancerization in HNSCC. In addition, interphase FISH is demonstrated as an effective technique for detecting chromosome aneuploidy associated with malignancy and a potential tool for non-invasive screening of individuals at high-risk for HNSCC.