The Correlation Between The Expressions Of Ki-67,p16 And Recurrence Of Parotid Pleomorphic Adenomas

Background:Pleomorphic adenomas are the most common tumors of the parotid gland. Postoperation recurrence was regarded to correlate with incomplete capsular,multinodules, inadequate surgical treatment of the primary tumor, et al. However, recurrent ratio of pleomorphic adenomas following excision of tumour with parotidectomy was reported to be as high as 3% or so, and some recurrent pleomorphic adenomas transformat malignance.So people think recurrence of parotid pleomorphic adenomas is correlated with the self-proliferative activity. Ki-67 is often used to evaluate cell proliferative capacity due to its continuous expression in proliferating cells, has become one of the most promising cell proliferative indexes recently .P16INK4/CDKN2 gene is a new tumor suppressor gene,thhis gene encodes a protein that binds to inhibit cyclin-dependent kinase 4(CDK4),plays a role in cell cycle regulation.Due to frequent inactivation of p16 gene in a lot of tumors,p16 gene has become a hot spot of molecular biological research in the past few years.we study the expressions of Ki-67and p16 in recurrent pleomorphic adenomas:among them ,include the primary(before recurrence)and second(after recurrence) operation groups,nonrecurrent group and normal parotid tissue group to explore the correlation between the expressions of Ki-67,p16 and recurrent biological behavior of parotid pleomorphic adenomas.Objective:To explore the correlation between the expressions of Ki-67,p16 and recurrent biological behavior of parotid pleomorphic adenomas.Furthermore, we want to evaluate the possibility of using them as the reference for prognosis.Methods:We followed up 1416 cases treated by standard (conventional) surgery for parotid pleomorphic adenomas. 17 cases of them were recurrent, and 11 paraffin specimen of which before and after recurrence were preserved well. We chose 20 specimen from no recurrent parotid pleomorphic adenomas over 10 years (mean 12.2 years) and 20 specimen from normal parotid tissue. We measured the positive expression rate of p16 and the lable index of Ki-67(LI)in each group by Envision immunohistochemical staining methods,and calculated proportional ratio of positive and strong positive expression of p16. Datas were analyzed by PEMS version 3.1 statistical software for windows,and the results were considered significant at p<0.05.Results :(1)Recurrent ratio of parotid pleomorphic adenomas after operation is 1.20%。(2)no significant statistical differences was showed in the lable index (LI )of Ki-67 between groups of before(2.68±0.50%) and after (3.00±1.20%)recurrent parotid pleomorphic adenoma (P>0.05);Both were significantly statistical differences from nonrecurrent group(1.35±0.61%)(P<0.05); all tumor groups were significantly statistical differences from normal parotid gland group(0.98±0.32%) (P<0.05). (3)Positive expression rate of p16 in normal parotid gland group(95.00%) was higher than the other three groups(P<0.05):before recurrence group (45.45%) ,after recurrence group(36.36%) , nonrecurrent group(60.00%); among the three groups, nonrecurrent group, s positive expression rate of p16 was the highest, while no significant statistical differences was showed in every two groups. Proportional ratio of positive and strong positive expression of p16 showed no significant statistical differences between groups of before(0%) and after recurrence(25.0%), groups of nonrecurrent(66.7%) and recurrent, groups of norecurrent and normal(P>0.05). Significant statistical differences were showed between normal group(89.5%) and before and after recurrence groups, nonrecurrent group and before recurrence group (P<0.05).Conclusions:1.As for a small sample study,parotid pleomorphic adenomas recurrence is correlated with the strong self-proliferative activity of tumors.2.The parotid pleomorphic adenomas with high LI of Ki-67 are more impossible to recurrence , the follow-up after surgery should be enhanced.3. p16 gene is correlated to the occurrence and recurrence of parotid pleomorphic adenoma, but this is not the only factor.