Ανοσοϊστοχημική μελέτη καρκινωμάτων τραχήλου μήτρας

Abstract

Matrix metalloproteinases (MMPs), their tissue inhibitors (TIMPs) and angiogenesis have been extensively assessed as prognostic markers in various types of tumors. Until now this research has not been rewarded with conclusive results and the assessment of the above markers has not been integrated in the routine of histopathology laboratories; however, interest in their study is being renewed by the development of new antineoplastic agents such as antiangiogenic drugs and synthetic MMP inhibitors. Among MMPs the collagénases MMP2 and MMP9 and the natural inhibitor of the former (TIMP2) seem to play a cardinal role in the spread of many tumors. These MMPs represent the driving force in proteolysis of extracellular matrix and in particular of basement membranes; therefore they are also closely involved in neoangiosis.The development of new and alternative treatment strategies for the cancer of uterine cervix makes even more relevant the study of additional non-anatomical prognostic markers as it is reasonably hoped that their use might assist stratification of patient and individualization of treatment.However, the biologic implications of the expression of each MMP / TIMP are not exactly clear; moreover there seems to be some controversy involved in the interpretation of micro-vessel density (MVD), tumor oxygenation and radiologic assessment of tumor vascularization. In this context we sought to evaluate the intensity of neoangiosis (MVD) and the immunohistochemichal expression of MMP2, MMP9, TIMP1 and TIMP2 in cervical cancer tissues and to study their relation with standard histopathologic parameters.MATERIALS AND METHODSThe inpatient clinical notes of 79 cases of invasive cervical cancer were retrospectively studied. Among these patients, 37 had radical hysterectomy and pelvic node resection for stage ΙΑ - IIA, 30 patients had been treated with primary radiotherapy for stage > MB and 12 patients previously undiagnosed had a simple hysterectomy. Tissue blocks from surgical specimens and biopsy material were retrieved, sectioned and submitted to immunohistochemical staining. Monoclonal rat IgG was used for immunostaining of MMP2, TIMP1 and TIMP2, polyclonal rabbit IgG was used for MMP9 and sheep anti-CD31 antibody was used to highlight the microvessels. Standard technique was used and incubation with the primary antibody at concentrations of 2 mcg/ml took place for 30 min. Histologic evaluation was undertaken by a senior histopathologist who was unaware as to the pathologic and clinical details of each case. This assessment was primarily conducted towards the core of each tumor, i.e. far from the invasive front. All slides were re-examined by the same examiner to reduce diagnostic error. The correlation of MMP/TIMP expression and MVD with major pathologic parameters was studied with fisher exact test.A subgroup of 18 cases having undergone radical surgery were considered to represent tumors of “low metastatic potential” as they demonstrated locally advanced disease with negative lymph nodes. The rates of expression of the MMPs, TIMPs and neoangiosis in this particular group were evaluated with fisher exact test.RESULTSHistologic assessment close to the center of the tumors showed that only a minority of cases stained positively for the studied collagénases and inhibitors: 37%, 24%, 16,5% and 5% of cases showed expression of MMP9, MMP2, TIMP2 and TIMP1 respectively. Immunostaining in the positive cases involved both tumour and stromal cells.MMP9 expression was strongly correlated with stage > IB1. The other correlations were not statistically significant but probably are of greater clinicopathologic significance: Immunostaining for MMP2 was associated with increased metastatic potential but this relation did not seem to be mediated through increased rate of lymph-vascular space involvement (LVSI). On the other hand, immunostaining for TIMP2 was associated with high likelihood of LVSI (OR = 8,1) but paradoxically it correlated also with low metastatic potential.Adenocarcinomas tended to show lower MVD but apart from this there was no other association of neoangiosis with MMP/TIMP expression or other pathologic parameters.DISCUSSIONIt is possible that a MMP2(+)/TIMP2(-) phenotype is associated with relatively less invasive but highly metastatic tumors whereas a MMP2(-) /TIMP2(+) phenotype is able to infiltrate deeply but fails to produce viable metastatic colonies due to impaired angiogenesis. This concept has been described in oral squamous cell cancers, it is consistent with the complex biologic activity of ΤΊΜΡ2 and is fully supported by our results.The lack of any association between MVD and MMPs/TIMPs, metastatic potential and histopathologic parameters in our study is consistent with a number of publications reporting absence of prognostic value in MVD. Although the majority of publications regard neoangiosis as a strong prognostic index in gynecologic cancers, it seems that the current method of MVD estimation is unable to discriminate between the manifestations of hypoxia in the core of a tumour and hypervascularity at the invasive front;Until refinement of the histologic assessment of neoangiosis, confusion will be perpetuated and important information will be missed.CONCLUSIONMMP2 and TIMP2 are important prognostic parameters in tumors of the uterine cervix. MMP9 is associated with advanced stage and TIMP1 is far less significant. The study of MMP2 and TIMP2 combined with an amended histologic method for evaluation of neoangiosis could offer important insight into the potential of a tumor to invade locally, to resist radiotherapy or to metastasize early. Developing prognostic markers for specific aspects of the biologie behavior of a tumor may be the way forward towards an optimal use of the new available therapeutic options.