Clinicopathologic evaluation of thyroid tumors through p53 protein accumulation and proliferative activity measured using Ki-67 and PCNA monoclonal antibodies

RESUMO

Thyroid neoplasms frequently present difficulties in the diagnostic and prognostic evaluation due to the poor relation between morphology and tumor behavior. It is particularly important to define parameters to evaluate the potential of aggressiveness of such neoplasias with ancillary techniques in order to improve the clinical management of the patients with thyroid tumors. The potential of three markers - p53, Ki-67 and PCNA - in adenocarcinomas of the thyroid was evaluated and the relation of these markers to the prognostic behavior of the tumors were analyzed in a retrospective study. Seventy-seven cases of patients with neoplasms of the thyroid, submitted to thyroid surgery by the same surgeon (RSC), belonging to the team, were studied. Histological sections of the samples were submitted to immunohistochemical reactions with anti-p53 (cione D07), anti-Ki-67 (clone MIB1) and anti-PCNA (clone PC 10) monoclonal antibodies. The positive demarcations were counted in 200 cells of selected areas. The results were correlated with clinical and histopathologic parameters, selected among the survival distributions for each category of a same variable, through the Cox-Mantel test. There were 14 p53 positive cases, 17 Ki-67 positive and ali cases were PCNA positive. Although Ki-67 is theoretically present in ali the phases of cell division, it was not possible to identify it in ali cases; PCNA, was shown as an identification marker with expressive sensitivity. The immunohistochemical study showed ali follicular adenocarcinomas with PCNA positive immunoreaction, 11 (36,6 percent) Ki-67 positive and 8 (26,6 percent) p53 positive; 30 papillary tumors were PCNA positive, 5 (16,6 percent) Ki-67 positive, and 6 (20 percent) p53 positive. Medullary and Hürthle cell adenocarcinomas showed only PCNA positive immunoreaction, 3 and 2 cases respectively. Regarding the undifferentiated adenocarcinomas, 5 specimens presented PCNA positive immunoreaction, 1 was Ki-67 positive, 3 were p53 positive. PCNA monoclonal antibody showed a positive correlation with patient age and histologic type (p=0.005 and p= 0.032 respectively).