Expression of bcl-2 in papillary thyroid cancers and its prognostic value

Papillary thyroid cancer has a good prognosis. This favourable prognosis may be attributed to the apoptotic tendency of the cancer cells. This study aims to evaluate the expression of bcl-2, which is an antidote of apoptosis, and aims to evaluate the value of bcl-2 as a prognostic marker in papillary thyroid cancer.

Bcl-2 expression in the archival materials of 31 patients with papillary thyroid cancer was examined with immunohistochemical methods using bcl-2 and p-53 stains. The results were compared with 31 normal thyroid tissue specimens, which consisted of the contralateral lobes of these patients. The results were then analyzed in accordance with the clinical features of the patients.

Thirty (96.7%) patients of the control group were positive for bcl-2 whilst one (3.3%) was negative. The staining for bcl-2 was positive in 12 (%75) patients with microcarcinomas (p < 0.05) and 13 (86.6%) with papillary cancers (p > 0.05). Two cases of the papillary cancer group were admitted to the hospital with local recurrence (6.4%) and both were positive for bcl-2 (p > 0.05). All cases (4/31), whose MACIS scores were higher than 7 were positive for bcl-2. Twenty-one of 27 cases whose MACIS scores were lower than 7 (77.7%) were positive for bcl-2 (p > 0.05). All tumours of this series were negative for p-53 immunstaining.

The rate of bcl-2 expression in microcarcinomas of papillary thyroid cancer decreases when compared to normal thyroid tissue. This may be an early sign of oncogenesis, and a reason for the favourable prognosis in microcarcinomas. However, bcl-2 cannot be used as a prognostic marker.