Evaluation Criteria for Chromosome Instability Detection by FISH to Predict Malignant Progression in Premalignant Glottic Laryngeal Lesions.

Background: The definition of objective, clinically applicable evaluation criteria for FISH 1c/7c in laryngeal precursor lesions for the detection of chromosome instability (CI). Copy Number Variations (CNV) for chromosomes 1 and 7 reflect the general ploidy status of premalignant head and neck lesions and can therefore be used as a marker for CI. Methods: We performed dual-target FISH for chromosomes 1 and 7 centromeres on 4 µm formalin-fixed, paraffin-embedded tissue sections of 87 laryngeal premalignancies to detect CNVs. Thirty-five normal head and neck squamous cell samples were used as a control. First, the chromosome 7:1 ratio (CR) was evaluated per lesion. The normal range of CRs (≥0.84 ≤ 1.16) was based on the mean CR +/− 3 x SD found in the normal population. Second, the percentage of aberrant nuclei, harboring > 2 chromosomes of chromosome 1 and/or 7 (PAN), was established (cut-off value for abnormal PAN ≥ 10%). Results: PAN showed a stronger correlation with malignant progression than CR (resp. OR 5.6, p = 0.001 and OR 3.8, p = 0.009). PAN combined with histopathology resulted in a prognostic model with an area under the ROC curve (AUC) of 0.75 (s.e. 0.061, sensitivity 71%, specificity 70%). Conclusions: evaluation criteria for FISH 1c/7c based on PAN ≥ 10% provide the best prognostic information on the risk of malignant progression of premalignant laryngeal lesions as compared with criteria based on the CR. FISH 1c/7c detection can be applied in combination with histopathological assessment.

Chromosome instability predicts progression of premalignant lesions of the larynx.

The histopathology of premalignant laryngeal lesions does not provide reliable information on the risk of malignant transformation, hence we examined new molecular markers which can easily be implemented in clinical practice. Dual-target fluorescence in situ hybridisation (FISH) for chromosome 1 and 7 centromeres was performed on tissue sections of laryngeal premalignancies in 69 patients. Chromosome instability was indicated by numerical imbalances and/or polysomy for chromosomes 1 and 7. Additionally, immunostainings for p53, Cyclin D1 and (p)FADD expression were evaluated. Malignant progression was recorded. Eighteen patients with carcinoma in situ (CIS) were treated after diagnosis and excluded from follow-up. Chromosome instability was strongly associated with a high risk of malignant transformation, especially in lower grade lesions (hyperplasia, mild and moderate dysplasia; odds ratio = 8.4, p = 0.004). Patients with lesions containing chromosome instability showed a significantly worse 5-year progression-free survival than those with premalignancies without chromosome instability (p = 0.002). Neither histopathology nor the protein markers predicted progression in univariate analysis, although histopathological diagnosis, p53 and FADD contributed positively to chromosome instability in multivariate analysis. Chromosome instability is associated with malignant progression of laryngeal premalignancies, especially in lower grade lesions. These results may contribute to better risk counselling, provided that they can be validated in a larger patient set.

Interobserver variability of laryngeal mucosal premalignant lesions: a histopathological evaluation.

The objective of this study is to measure interobserver variability in the classification of laryngeal mucosal premalignant lesions by reassessing the histopathology of previously diagnosed cases and to determine the possible therapeutic consequences of disagreement among observers. Histopathological assessment of 110 laryngeal mucosal premalignant lesions was done by three pathologists. Each slide had to be classified according to the World Health Organization, Squamous Intraepithelial Neoplasia, and the Ljubljana Squamous Intraepithelial Lesions systems. After the independent assessment, a joint meeting took place. To assess the relation between histopathological grading and subsequent clinical management, we created a two- and a three-grade system besides one comprising all options. For all analyses, the SAS/STAT statistical software was used. The highest unweighted κ-values concerning the all-options system are observed for the Squamous Intraepithelial Neoplasia classification (0.28, 95% confidence interval 0.23-0.33), followed by the World Health Organization and Ljubljana classifications. For the two-grade system the Ljubljana classification shows the highest unweighted κ-values (0.50, 95%, 0.39-0.61), followed by the World Health Organization and Squamous Intraepithelial Neoplasia classifications. For the three-grade system, the unweighted κ-values are similar. The implementation of weighted κ-values led to higher scores within all three classification systems, although these did not exceed 0.55 (moderate agreement). Given the high level of consensus, simultaneous pathological assessment may be said to provide added value in comparison with independent assessment. In the current study, no clear tendency is observed in favor of any one classification system. The proposed three-grade system could be an improved histopathological tool because it is easier to correlate with clinical decision making and because it yields better unweighted κ-values and proportions of concordance than the all-options system. Furthermore, clinical management could benefit from assessment by more than one pathologist in suspected cases of dysplasia or carcinoma.