Stathmin is superior to AKT and phospho‐AKT staining for the detection of phosphoinositide 3‐kinase activation and aggressive endometrial cancer

Background: Although endometrial cancer in general has a good prognosis, 15-20%recurs. Surgery is the main treatment with lymph node sampling increasinglyadvocated as compulsory for adequate staging. In metastatic disease, there is limitedeffect from systemic therapies including chemotherapy or antihormonal treatment. Noother targeted therapies are yet available in a routine clinical setting. To improve andindividualise therapy for this patient group, improved tools for identification of highriskpatients, to tailor surgery in particular, and identification of targetable molecularalterations for development of more effective systemic therapies, are urgently needed.Several biomarkers including hormone receptor status, TP53 and Stathmin expressionhave been found to be of prognostic importance in retrospective studies. ThePI3Kinase signalling pathway is over-expressed in aggressive endometrial carcinomasand PI3kinase inhibitors are entering clinical trials for treatment of metastatic disease.Main objectives: The main objective was to evaluate if biomarkers, particularlyexamined in a preoperative setting, could identify aggressive endometrial carcinomas,especially those with lymph node metastasis. An additional aim was to evaluateimmunohistochemical markers potentially applicable as markers for response toantihormonal therapy and PI3Kinase-inhibitors. Also, we wanted to study changes intreatment strategy in relation to survival for endometrial carcinoma patients during a30-year period in a population based setting.Materials and methods: To evaluate potential biomarkers related to PI3Kinasesignalling, a population based cohort was investigated for immunohistochemicalexpression of AKT, Phospho-AKT and Stathmin in hysterectomy specimens. Thesemarkers were also related to level of PI3Kinase signalling based on mRNAexpression score in a prospective series of 76 patients (Paper I).The prospective international multicenter study MoMaTEC; Molecular Markers inTreatment of Endometrial Cancer, recruited clinical data, tissue and blood samplesfrom 1192 endometrial cancer patients treated at 10 different centres during 2001-2010. Preoperative curettage specimens and blood samples have been investigated forexpression of a panel of potential biomarkers; Stathmin, Estrogen Receptor (ER),Progesterone Receptor (PR), TP53 and GDF-15 (Paper II, III and IV).Changes in clinicopathological features and treatment were related to survival in apopulation based cohort of endometrial cancer patients from Hordaland County,Norway over the last 30 years (Paper V).Results: Stathmin overexpression in hysterectomy specimens was strongly correlatedwith characteristics for aggressive disease and poor survival. PI3Kinase signallingactivation was significantly associated with overexpression of Stathmin. Neither AKTnor phospho-AKT expression showed any significant correlations withclinicopathological factors nor PI3Kinase signalling levels (Paper I).Overexpression of Stathmin validated to be correlated with aggressive disease in thelarge prospective multicentre setting (Paper II). Stathmin staining in curettagespecimens was an independent predictor of lymph node metastases andoverexpression of Stathmin estimated in curettage and hysterectomy specimens wereboth independent predictors of poor survival.High preoperative plasma GDF-15 level was significantly associated with aggressivedisease. Adjusting for age and histological risk factors detected in preoperativebiopsies, plasma GDF-15 independently predicted risk of lymph node metastasis.GDF-15 level also independently predicted poor prognosis (Paper III).Pathologic expression of ER, PR and TP53 in preoperative curettage specimencorrelated significantly with high age at diagnosis, high FIGO stage, nonendometrioidhistology, high grade, metastatic nodes and poor prognosis in a largeprospective multicenter setting. Double negative ER-PR independently predictedlymph node metastasis and poor survival. Even for the most favourable group oflymph node negative endometrioid tumours, ER-PR negative status influencedsurvival independent of tumour grade (Paper IV). The number of endometrial cancer patients from Hordaland County increasedsignificantly from 1981 through 2010 (Paper V), with a simultaneous increase inbody mass index and decrease in disease stage at diagnosis. Routinely performedpelvic lymph node sampling increased, adjuvant radiotherapy was reduced andsurvival increased significantly during the same period.Conclusions: Stathmin immunohistochemical staining is superior to AKT andphospho-AKT staining in detecting PI3Kinase signalling activation and endometrialcarcinomas with poor outcome (Paper I).Stathmin staining has been validated to identify endometrial carcinomas withaggressive clinic-pathological features in a large multicenter setting.Immunohistochemical staining for Stathmin in preoperative biopsies (curettage)independently predicts lymph node metastasis and poor survival (Paper II).Plasma GDF-15 has been documented as elevated in two independent patient cohortsof endometrial cancer patients compared to controls. High preoperative GDF-15plasma level was significantly correlated with aggressive subtypes and a significantand independent predictor for lymph node metastasis and poor survival (Paper III).Double negative hormone receptor status (ER and PR negative) in preoperativeendometrial cancer curettage has been validated to identify patients with poorprognosis in a prospective multicenter setting. ER-PR status independently predictslymph node metastasis (Paper IV).During the 30-year period 1981 through 2010, a reduction in adjuvant radiotherapyand increase in routine pelvic lymphadenectomy and curative surgery with advanceddisease, are associated with improved disease-specific- and overall survival in apopulation-based study of endometrial carcinoma patients with steadily increasingbody mass index (Paper V)