Deoxyribonucleic acid ploidy studies in choroidal melanomas

The correlation between cell surface markers and clinical features in choroidal malignant melanomas

PURPOSE

Uveal melanoma continues to present problems when attempting to predict disease progression. This study attempts to identify markers indicative of the biological characteristics of cells isolated from samples of uveal melanoma, including adhesion (ICAM-1), immune reactivity (MHC Class I and II), cell cycle control (c-erbB-2, c-myc) and apoptosis control (bcl-2, p53) using dual parameter (DNA/MoAb) flow cytometry.

METHODS

Sixty-three fresh tissue samples from choroidal melanomas were taken at enucleation. Samples were assayed for DNA content and cell cycle, the above antibodies together with positive (PHM-5) and negative (2 degrees FITC Ab) controls. The clinical parameters sex, age, tumour location, cell type, tumour volume and presence of metastases were compared with the results and analysed with the non-parametric Mann-Whitney U-t-test.

RESULTS

ICAM-1 expression proved to be the most clinically relevant, being present on a higher proportion of cells in tumours > 2000 mm3 (median 38, n = 19) compared with the smaller tumours < 2000 mm3 (median 17, n = 26) (p = 0.0015). Metastatic disease was present in 11 patients and did not correlate with any of the surface markers. C-myc, c-erbB-2 and MHC Class II expression were associated with cell type, all showing greater expression in spindle cell tumours than mixed/epithelial types.

CONCLUSION

These results show flow cytometry as a quick, easy method to provide a 'phenotypic profile' for these tumours, and identifies cell cycle control and adhesion molecule expression as important areas for further investigation. c-erbB-2 and bcl-2 positivity was typically seen on over 60% cells in each sample, indicating two potential targets for therapeutic intervention.

DNA index and % S phase fraction in posterior uveal melanoma: a 5 year prospective study of fresh tissue using flow cytometry

In many different solid tumours the DNA content of cells has been reported to be associated with malignancy. With one exception, studies using flow cytometry to estimate cellular DNA in uveal melanoma have used archival material. We report the findings of a prospective study using fresh uveal melanoma where the DNA index (DI) and percentage of cells in S phase (%SPF) have been determined by flow cytometry in 51 patients with a minimum follow-up of 5 years. Forty-one (80%) of the tumours were large, 9 (18%) were medium and only 1 was small. Eight (16%) were epithelioid tumours, 41 (80%) were mixed cell and only 2 were spindle B cell tumours. Twenty-seven tumours were diploid, of which 10 (37%) developed metastases. Of the 24 aneuploid tumours, metastases developed in 6 (25%). The median %SPF was significantly reduced in patients with diploid tumours compared with aneuploid tumours (p < 0.0001), but there were no significant differences in %SPF between tumours associated with or without metastatic disease. The DI and %SPF were not significantly associated with the operation performed, cell morphology, tumour size or location. Neither %SPF nor aneuploidy was associated with a poor prognosis. Our results suggest that the estimation of DI or %SPF by flow cytometry is of little value in predicting survival from uveal melanomas after a minimum follow-up of 5 years.

Prognostic parameters in uveal melanoma: a review

Histologic cell type, largest tumor diameter and tumor location have traditionally been regarded as the leading predictors of survival for uveal melanoma. Morphological cell typing is, however, subjective to variations in interpretation. More objective classification parameters have emerged from extensive cytomorphometrical and DNA flow cytometrical studies. For patients with uveal melanoma there is no effective therapy if metastases have developed, and the median survival after clinical diagnosis of hepatic metastases is extremely poor. Current research focuses on the mechanisms underlying the metastatic process, including tumor vasculature, cytogenetics, oncogene activation, immunology, melanoma-associated antigens and tumor cell migration (cell-cell and cell-matrix interaction). Several new prognostic parameters have emerged from these studies, such as closed vascular patterns, loss of one chromosome 3, and different indices of cell proliferation. Furthermore, considerable genotypical and phenotypical differences have been found between uveal and cutaneous melanoma. In prospective studies on large series of melanomas a combination of histopathological and/or clinical prognostic parameters might be selected with high sensitivity and specificity, providing a way of selecting patients at high risk of developing metastatic disease, who might be eligible for adjuvant therapy.

DNA flow cytometry in uveal melanoma: the effect of pre-enucleation irradiation

BACKGROUND

For uveal melanoma it has been demonstrated that aneuploidy correlates with worse clinical outcome. However, a striking variation in incidence of aneuploidy is reported for uveal melanomas.

METHODS

Flow cytometry was used to study retrospectively DNA-ploidy of 132 uveal melanomas on paraffin embedded material. Thirty five patients received 2 x 4 Gy doses of irradiation 24 and 48 hours before enucleation. Correlation between DNA-ploidy and histopathological grading, largest tumour diameter, tumour height, tumour location, scleral invasion, and TNM classification was assessed. Survival analysis methods were used to investigate the predictive value of these variables on clinical outcome.

RESULTS

Of the tumours 37% were aneuploid and 63% were diploid. Intratumour ploidy heterogeneity was minimal (92% concordance). A strong correlation (p = 0.009) was found between DNA-ploidy and cell type. No correlation was found between DNA-ploidy and other conventional prognostic variables. Irradiated melanomas were significantly more aneuploid than non-irradiated tumours (p < or = 0.01).

CONCLUSION

In survival analysis DNA-ploidy and the largest tumour diameter were significant in predicting metastatic outcome (p < or = 0.03 and 0.01 respectively); histological cell type and tumour location were of borderline significance.

DNA ploidy and S-phase fraction as prognostic factors in patients with uveal melanomas

In 96 patients with uveal malignant melanomas the tumours were investigated by DNA flow cytometry. Thirty-eight per cent of the melanomas were aneuploid. By univariate analysis significant correlations with survival were found for histological type, tumour size, DNA ploidy, evidence of 'blind eye' and S-phase fraction. By multivariate analysis, significant prognostic variables were found to be histological type (P = 0.0008), tumour size (P < 0.0001) and DNA ploidy (P = 0.0038). Evidence of 'blind eye' was not significantly correlated with survival after adjustments for the other variables mentioned above. The S-phase fraction could be estimated in all 60 diploid tumours and in 12 of 36 aneuploid melanomas. By univariate analysis this variable was found to be a significant prognostic factor, but did not remain so after adjustment for ploidy, histological type and tumor size. We further conclude that patients with small DNA diploid uveal melanomas of spindle cell type have a rather favourable prognosis.

DNA ploidy status in 84 ocular melanomas: a study of DNA quantitation in ocular melanomas by flow cytometry and automatic and interactive static image analysis

Deoxyribonucleic acid (DNA) ploidy was quantified in 84 ocular melanomas (median follow-up, 11-years) by flow cytometry, CAS 200 interactive image analysis, and Pathology Image Processing Environment (PIPE; Department of Quantitative Pathology, Free University, Amsterdam, The Netherlands) automatic image analysis (75). Overall, 32.1% of the melanomas were aneuploid, 2.3% were tetraploid, and 66.6% were diploid. Pathology Image Processing Environment analysis estimated DNA ploidy in 12 tumors that were unprocessable by flow cytometry. Of 10 tumors that were diploid by flow cytometry, PIPE detected stemline aneuploidy in five and some aneuploid cells in five more. Seven tumors were aneuploid by PIPE but diploid by CAS 200, five of which contained occasional DNA aneuploid cells on the CAS 200 histograms. Pathology Image Processing Environment analysis quantified tumor samples with an average of 500 (250 to 1,050) cells in less than 10 minutes. All cells classified as spindle A according to the Callender system (more than 10,000) were diploid. Spindle B and epithelioid cells occupied both diploid and aneuploid peaks on the DNA histograms. Dioxyribonucleic acid variables did not correlate with established prognosticators, such as Callender cell type, largest tumor dimension, or glaucoma, nor did they reach significance by univariate and multivariate analyses. The value of these findings as a diagnostic support in uveal melanoma, particularly in combination with fine needle aspiration biopsy, is discussed.

Syntactic structure analysis in uveal melanomas

Syntactic structure analysis was carried out successfully on 92 paraffin embedded uveal melanomas, taken from patients with a minimum follow up of 5 years. This simple, fast, and reproducible method of describing the tumour architecture has been significantly correlated with malignancy in tumours from several sites. Paraffin sections 5 microns thick, were cut and stained with haematoxylin and eosin. Tumours were classified according to a modification of the Callender classification. A minimum spanning tree (MST), using the centre points of tumour nuclei, was constructed in five randomly chosen fields with an interactive digitising video overlay system. Ten syntactic structure features were derived from each MST; subsequently, the mean and standard deviation of the five fields analysed were calculated for further statistical analysis. Reproducibility was acceptable with a mean correlation coefficient of 0.70. In univariate survival analysis, the percentage of points with three neighbours yielded prognostic significance (p < 0.05). Minimum spanning tree variables were compared (chi 2 test) with classic tumour prognosticators and there was a significant correlation between Callender cell type and the following MST parameters: mean number of points (p < 0.003); MST length (p < 0.003); mean line length (p < 0.01); number of nuclei with one neighbour (p < 0.004); number of nuclei with two neighbours (p < 0.02), and number of nuclei with three neighbours (p < 0.005). Syntactic structure analysis is an evolving technique, but may be able to mathematically (and reproducibly) describe melanoma architecture across the spectrum of the Callender classes. This would also allow architectural grading of tumours within the specific Callender groups, providing more precise prognostic information. Further modifications of this technique are necessary to optimise prognostic potential when applied to uveal melanomas.

Prognostic factors following enucleation of 111 uveal melanomas

Follow up information was retrieved on 111 patients who underwent enucleation for uveal melanoma between 1964 and 1987, allowing a minimum postoperative period of 5 years. Univariate survival analysis was carried out using Kaplan-Meier curves and the differences between the curves were analysed with the Mantel-Cox test. Multivariate analysis used the Cox proportional hazards model. Univariate analysis isolated each of the following as significant prognosticators: largest tumour diameter (LTD) (p < 0.002), presence of epithelioid cells (p < 0.03), and glaucoma (p < 0.001). A combination of cell type, glaucoma, and LTD (p < 0.0001) had strong and independent prognostic significance in multivariate analysis. The results of this series are compared with previous studies and the value of cell type information and new quantitative parameters is discussed.