Clinical and pathological assessment of survivin and bax in the discrimination between follicular adenoma and carcinoma of the thyroid

Abstract EN

Background : Thyroid nodules can be the result of a wide spectrum of causes, and a major concern is to accurately differentiate between benign and malignant nodules, especially tumors with follicular pattern.

Surviving is one of the 8 members of human inhibitor of apoptosis IAP family, which is differentially expressed in cancerous/ transformed cells versus normal / differentiated cells.

While Bax is one of Bcl2 family that acts as a pro-apoptotic gene.

Objectives : This study aimed to assess the clinical usefulness of surviving and Bax immunostaining for discrimination between follicular adenoma and carcinoma of thyroid.

Patients and methods : Thirty patients with follicular thyroid lesions were admitted at the surgery department, MRI hospital, Alexandria University, from January 2006 to June 2007.

All patients were subjected to ultrasound, and FNAC of the thyroid before surgical intervention.

Fifteen cases of follicular adenomas and adenomatous goiters (FA), serve as comparative control to five cases of follicular adenomas with incomplete capsular penetration (FAICP), and ten cases of follicular carcinomas (FC).Tissue sections from each case were immune- stained by antibodies to surviving and Bax .

Results : Significant differences were noted between surviving (p=0.003) and Bax (p=0.03) expressions in benign and malignant cases.

Significant differences were found between FA, FAICP and FC regarding Patient’s age (p=0.002), tumor size (p=0.05), and mitotic count (p=0.012).

Changing the staining pattern of surviving from nuclear in benign adenomas which reflects its regulation of proliferation and differentiation, to nucleocytoplasmic and cytoplasm anti-apoptotic effect in FC was noted in the studied material.

Surviving expression was higher in widely invasive than minimally invasive tumors (p=0.03).

Bax expression was lower in high grade follicular carcinoma (P =0.006), and in advanced stages (p=0.003).

Its expression was seen in tumor associated lymphocytes, inducing their apoptosis, thus allow malignant cells to evade immune surveillance.

Conclusions : Thus, surviving and Bax can discriminate between follicular adenomas and carcinomas; Alteration of their expression may contribute to the pathogenesis of thyroid carcinomas, surviving is a marker of poor prognosis.

Therefore, it could be speculated that Anti-surviving new therapies may not only potentiate chemotherapies that stimulate apoptosis, but, may also exert an ant proliferative effect.