engleski

Expression of intratumoral microvessel density and oncoproteins in papillary thyroid carcinomas with and without metastases

Differentiated carcinoma of the thyroid is considered to be biologically relatively indolent neoplasm characterized by a favorable outcome following adequate surgical treatment. However, about 30% of the tumors followed unexpected course and behave in highly malignant fashion, showing poor prognosis. Therefore, in order to investigate whether intratumoral microvessel density and immunohistochemical expression of bcl-2 and p53 could serve to indentify subgroup of patients with more agressive behavior of the tumor we: 1. analyzed intratumoral microvessel count (MVC) and intratumoral microvessel density (MVD), expresssion of oncoprotein bcl-2 and tumor supressor protein p53 in 50 localised papillary carcinomas (LPC), 50 papillary carcinomas of the thyroid gland with metastatic involvement of regional lymph nodes (PCMLN), 50 associated metastatic tumors (M) and normal thyroid gland tissue 2. compared intratumoral microvessel density, tumor histologic grade, expresssion of oncoprotein bcl-2 and tumor supressor protein p53 between localised papillary carcinomas (LPC) and papillary carcinomas of the thyroid gland with metastatic involvement of regional lymph nodes (PCMLN) 3. analyzed the relationship between intratumoral microvessel density, expresssion of oncoprotein bcl-2 and tumor supressor protein p53 with clinical parameters icluding age, sex, and tumor size. The study was carried out by immunohistochemistry on paraffin embedded material. Formalin fixed, paraffin embedded tissue was cut at 5 mm, deparaffinized and stained with monoclonal antibody to human Von Willebrand Factor H0079 (Factor VIII related antigen), antibody DO-7 H7123 to p53 (Dako, Denmark) and antibody124 H7124 to bcl-2 (Dako, Denmark) following Microwave Streptavidin ImmunoPeroxidase (MSIP) protocol on DAKO TechMateTM Horizon automated immunostainer. The invasive tumors were often heterogeneus with respect to the amount and distribution of microvessels and sections were therefore examined at low magnifications (x40, x100) to identify most vascular area of the tumor (&#8220 ; hot spot&#8221 ; ). Within these &#8220 ; hot spots&#8221 ; counting was done in 10 non-overlapping consecutive high power magnifications fields (x400 / 0, 144mm2). The average MVC was calculated from 10 vascular &#8220 ; hot spots&#8221 ; , and was also expressed as MVD/mm2 of the tumor area. Immunohistochemical examination was recorded semiquantitativelly, considering both the intensity of staining and proportion of tumor cells showing an unequivocal immunoreactivity. Immunohistochemical staining index (ISI) = staining intensity (SI) + percent of reactive tumor cells (PRS). In subsequent analyses using ISI, categories were grouped to achive maximum discrimination. Statistical analysis was performed by statistical package SAS 6.12 and STATISTICA 6.0 using Student T-test, Mann-Whitney U-test, c2-test, Fisher-exact test, ANOVA test, Pearson correlations and Spearman rank correlations. The level of significance was set at P<0.05 in all cases. We observe statistically significant difference in the MVD between localised papillary carcinomas (LPC), and papillary carcinomas of the thyroid gland with metastatic involvement of regional lymph nodes (PCMLN) (p<0, 001). We observe statistically significant difference in the MVD between G1(low grade) and G2 (high grade) papillary carcinomas (p<0, 001). We observe statistically significant difference in the expression of bcl-2 (p=0, 008) and p53 (p<0, 001) between LPCs and PCMLNs, with significant increase of ISI values in PCMLN group. Also we observe statistically significant higher values of ISI in G2 (high grade) carcinomas compared with G1 (low grade) carcinomas. We observe statistically significant correlation between microvessel density (MVD) and expression of p53 (p<0, 001) and expression of bcl-2 (p=0, 009). Finally our results suggest that intratumoral microvessel density (MVD), bcl-2 and p53 expression in papillary carcinomas of the thyroid gland may help to identify a group of patients at high risk, associated with more aggressive biological behaviour of these tumors, who can benefit from new terapies sach as angio-genesis-inhibiting drugs and adjuvant radiotherapy following more extensive surgical treatment, accompanied with careful follow up. This selective approach will might lead us to avoid unnecessarily aggressive treatment for tumors that are likely to follow benign course, and inadequate therapy for others anticipated to display aggressive behavior.

intratumoral microvessel; oncoproteins; papillary thyroid carcinoma

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