Preoperative Thrombocytosis and Poor Prognostic Factors in Endometrial Cancer

Haemostatic abnormalities are frequently observed in patients with malignancy. Most patients with cancer have evidence of subclinical activation of blood coagulation. Clinically, cancer patients with advanced disease are characterized by a variety of venous thromboembolic disorders. The mechanistic framework that helps to understand and group the causes of thromboembolism is an extension of the triad of Virchow, which postulates that thrombosis is caused by changes in blood flow, the state of the vessel wall, and/or the composition of blood. Platelets have historically been ignored in studies of VTE. Several lines of research indicate though that platelets play a determining role nowadays. Common and well-established risk factors and presumed points of action of malignancy that cause thromboembolism were microparticles, innate immunity and platelet numbers (Pieter et al., 2012). The association between elevated platelets counts and malignancies was recognized over a century ago (Riess, 1872). Thrombocytosis (generally defined as platelet count greater than 400000/μL) has


Introduction
Haemostatic abnormalities are frequently observed in patients with malignancy.Most patients with cancer have evidence of subclinical activation of blood coagulation.Clinically, cancer patients with advanced disease are characterized by a variety of venous thromboembolic disorders.The mechanistic framework that helps to understand and group the causes of thromboembolism is an extension of the triad of Virchow, which postulates that thrombosis is caused by changes in blood flow, the state of the vessel wall, and/or the composition of blood.Platelets have historically been ignored in studies of VTE.Several lines of research indicate though that platelets play a determining role nowadays.Common and well-established risk factors and presumed points of action of malignancy that cause thromboembolism were microparticles, innate immunity and platelet numbers (Pieter et al., 2012).The association between elevated platelets counts and malignancies was recognized over a century ago (Riess, 1872).Thrombocytosis (generally defined as platelet count greater than 400000/µL) has
Endometrial cancer is the most common cancer of the female genital tract in developed countries.Abnormal vaginal bleeding, especially in postmenopause, is the most common presenting symptom in patients with endometrial cancer and the majority of cases are diagnosed while the disease is confined in the uterine corpus.In Thailand, it is the third most common gynecological malignancy after cervical and ovarian cancer with an annual incidence of 4.3 per 100,000 women, and an annual death rate of 1.1 per 100,000 women per year (Ferlay et al., 2010).Only few data are currently available concerning the association between thrombocytosis and prognostic factors in endometrial cancer (Menczer et al., 1996;Gucer et al., 1998;Scholz et al., 2000;Tamussino et al., 2001;Ayhan et al., 2006;Metindir and Dilek, 2009).To the best of our knowledge, there are no reports investigating such a relationship in Thailand.The objective of our study was to determine the prevalence and prognostic value of preoperative thrombocytosis in Thai women with endometrial cancer.

Materials and Methods
The hospital records of patients with histologically confirmed endometrial cancer who underwent primary surgical staging procedure at the Department of Obstetrics and Gynecology, Siriraj Hospital were reviewed.Surgical staging procedure consisted of total hysterectomy with bilateral salpingo-oophorectomy with selective pelvic and paraaortic lymph node dissection.Peritoneal washing for cytology was optional.Criteria for selective pelvic and paraaortic lymph node dissection were tumor size larger than 2 cm in greatest diameter, high grade endometrioid carcinoma (grade 2 or 3), deep myometrial invasion (>50% of myometrial thickness), or some specific histology (serous or clear cell).The tumor stage and histological diagnosis of each case were surgically determined according to the criteria of the International Federation of Gynecology and Obstetrics (FIGO staging system, 2009) and the histological classification of the World Health Organization (WHO), respectively.Endometrioid tumors were graded as well (G1), moderately (G2), or poorly (G3) differentiated.Adjuvantly, patients with high grade tumor, serous or clear cell histology, deep myometrial invasion, cervical extension, adnexal involvement, positive peritoneal cytology, and lymph node metastasis received radiotherapy, or chemotherapy, or both.Patients without these histological factors received no adjuvant treatment.Patients with missing preoperative platelet counts, having concurrent other malignancy or conditions associated with thrombocytosis (i.e., collagen vascular disease, secondary malignancies, and chronic obstructive pulmonary disease) were excluded from the analysis.
Blood platelet count in each patient was obtained within 2 weeks prior to the surgery.Thrombocytosis was defined as platelet count of greater than 400000/µL consistent with prior reports in the literature (Costantini et al., 1990;Zeimet et al., 1994;Pedersen and Milman, 1996;Gucer et al., 1998;O'Keefe et al., 2002;Gorelick et al., 2009).Data were analyzed using χ 2 test, student t-test and Fisher exact test as appropriated.Association between clinicopathological variables (histology, grading, stage, myometrial invasion, lymphovascular space invasion, cervical involvement, adnexal involvement, peritoneal cytology, and lymph node status) and preoperative platelet counts were described using Pearson's chi square test (or two-tailed Fisher's exact test wnen appropriate).Survival analysis was performed with Kaplan-Meier estimates.Univariate and Cox-regression models were used to evaluate the prognostic impact of various factors including platelet count in terms of disease-free survival and overall survival.Data management and statistics were analyzed using PASW statistics 18.0 (IBM Corporation, New York, NY, USA).A p-value of <0.05 was taken for statistical significance.The research project was approved by the ethical committee of the Siriraj Hospital, Mahidol University, and was conducted in accordance with the Declaration of Helsinki.

Results
Between January 2005 and December 2008, 251 patients with endometrial cancer underwent surgical staging at the Department of Obstetrics and Gynecology, Siriraj Hospital.Thirteen patients were excluded from the study because of missing pretreatment platelet counts, having concurrent other malignancy and conditions associated with thrombocytosis, so the remaining 238 patients were qualified for the final analysis.The age range of the patients was 28-88 years with a mean age of 57.88+10.03years.Histologically, while 196 (82.4%) patients were endometrioid, the remaining 42 (17.6%)had non-endometrioid histology.Tumor grade among 196 patients with endometrioid histology was G1 in 109 (55.6%) patients, G2 in 65 (33.2%), and G3 in 22 (11.2%).Stage of the disease was early in the majority of the patients (68.9% stage 1, 9.2% stage 2).Approximately one third of the patients had deep myometrial invasion.Thirty-nine (17.2%) of the 227 patiens was found to have lymphovascular space invasion.Cervical and adnexal involvement was observed in 44 (18.5%) and 29 (12.2%)patients, respectively.Twenty-two (10.9%) of the 201 patients had positive peritoneal cytology.Among 198 patients who underwent lymphadenectomy, 23 (11.6%) had nodal involvement, and the remaining did not.Ninetyfive patients (39.9%) received radiation only, 25 (10.5%) received chemotherapy only, 10 (4.2%) received both radiation and chemotherapy, and 108 (45.4%) received no adjuvant treatment.The median duration of follow-up was 59.6 months (range, 1.0-98.0months) and median overall survival was not reached.The 5-year disease-free survival and overall survival probability were 81.9% and 93.3%, respectively.At the end of the observation period, 193 patients (81.1%) were tumor free, 28 patients (11.8%) were alive with tumor, 15 patients (6.3%) had died of their disease and 2 patients (0.8%) had died from non-cancer related conditions.
Overall mean preoperative platelet count was 315437/ µL (SD 100167/µL).Patients who had advanced stage, adnexal involvement, lymph node metastasis, and positive peritoneal cytology had significantly higher mean preoperative platelet counts when compared with those who had not (Table 1).One hundred and ninetyfive patients (81.9%) of patients had a preoperative DOI:http://dx.doi.org/10.7314/APJCP.2014.15.23.10231Preoperative Thrombocytosis as a Prognostic Factor in Endometrial Cancer platelet count lower than 400000µL, while the remaining 43 (18.1%)exhibited preoperative thrombocytosis.Correlation between thrombocytosis and baseline patients' characteristics are given in Table 2.These 43 patients with thrombocytosis had significant higher rates of advanced FIGO stage, cervical involvement, adnexal involvement, positive peritoneal cytology, and lymph node involvement than patients with normal pretreatment platelet count (<400000/µL).The 5-year disease-free survival and overall survival were significantly lower in patients    1,2).Univariate and multivariate analysis to demonstrate the prognostic influence of all variables in term of 5-year disease-free survival and overall survival are shown in Tables 3 and  4. The independent predictors for poor disease-free survival and overall survival could be determined only for deep myometrial invasion, and lymph node metastasis, respectively.

Discussion
One of the principle causes of death in patients with cancer is thromboembolism.The pathophysiological mechanisms inducing hypercoagulability in cancer patients are complex (Pieter et al., 2012).Reactive thrombocytosis is among the haemostatic abnormalities commonly observed in neoplastic diseases.It is prevalent in a wide range of malignancies and has been estimated to occur in about 10% to 57% of all patients (Sierko and Wojtukiewicz, 2004).The frequencies of thrombocytosis in patients with endometrial cancer have varied between 1.5% and 18.2% (Menczer et al., 1996;Gucer et al., 1998;Scholz et al., 2000;Tamussino et al., 2001;Ayhan et al., 2006;Metindir and Dilek, 2009).The pathophysiological mechanism of thrombocytosis in malignancy may be tumor-associated elevations of circulating platelets mediated by a direct promotion of megakaryocytopoiesis by tumor-derived humoral factors.Plasma levels of interleukin-6 and thrombopoietin have been found to be significantly elevated in patients who have thrombocytosis as compared with those who have not.Interleukin-6 is a potent stimulator of megakaryocytopoiesis and tumor cells have been shown to release IL-6 both in vitro and in vivo.In mouse models, increased hepatic thrombopoietin synthesis in response to tumor-derived interleukin-6 is an underlying mechanism of reactive thrombocytosis.Tumor-derived interleukin-6 and hepatic thrombopoietin have also been demonstrated to be linked to thrombocytosis in patients with cancer (Nakazaki, 1992;Lidor et al., 1993;Kabir and Darr, 1995;Wu et al., 1996;).Elevated levels of platelet counts have been demonstrated to be a significant prognostic factor in a variety of solid tumors, including endometrial malignancy (Menczer et al., 1996;Gucer et al., 1998;Scholz et al., 2000;Tamussino et al., 2001;Ayhan et al., 2006;Metindir and Dilek, 2009).
The prevalence of thrombocytosis in endometrial cancer found in this study (18.1%) is in agreement with previous reports (Menczer et al., 1996;Gucer et al., 1998;Scholz et al., 2000;Tamussino et al., 2001;Ayhan et al., 2006;Metindir and Dilek, 2009).Few data are currently available about the clinical relevance of anemia in endometrial cancer.In the first retrospective study by Menczer et al. (1996) only one of 66 patients with endometrial cancer (1.5%) had preoperative platelet count greater than 400000/µL in blood samples drawn prior to surgery.However, a significant correlation was found between an elevated platelet count (≥300000/µL) and unfavorable grade of differentiation and patients with an elevated count also had a poorer survival rate (Menczer et al., 1996).Subsequent studies reported higher prevalence of thrombocytosis, ranging from 7.7% to 18.2% and revealed the relation between preoperative thrombocytosis and poor prognostic factors in patients with endometrial cancer (Gucer et al., 1998;Scholz et al., 2000;Tamussino et al., 2001;Ayhan et al., 2006;Metindir and Dilek, 2009).However, the association between thrombocytosis and survival has been questionable in multivariate analyses.Gucer  between increasing preoperative platelet count and poor prognostic factors, such as advanced-staged disease, poorly differentiated tumor grade, deep myometrial invasion, and lymphovascular space invasion.The 5-year overall survival rate of patients with thrombocytosis was significantly worse than those with preoperative normal platelet count.However, the author did not perform a multivariate analysis of thrombocytosis (Gucer et al., 1998).Scholtz et al. also confirmed that 5-year diseasefree survival and overall survival rates of patients with advanced endometrial cancer were significantly influenced by stage, cervical involvement, and thrombocytosis (Scholz et al., 2000).According to the results of Tamussino et al. thrombocytosis was associated with advanced disease, unfavorable grade, and non-endometrioid histology in the presence of anemia in endometrial cancer patients (Tamussino et al., 2001).In 2006, Ayhan et al. studied retrospectively 155 endometrial cancer patients who underwent surgical treatment consisting of total abdominal hysterectomy, bilateral salpingo-oophorectomy, infracolic omentectomy, systematic pelvic and para-aortic lymph node dissection, and peritoneal cytology.The author demonstrated that advanced stage, poor grade, the presence of cervical and adnexal involvements are associated with preoperative platelet counts in patients with endometrial cancer (Ayhan et al., 2006).Metindir et al. found that higher median preoperative platelet counts were significantly associated with the presence of cervical involvement and lymph node metastasis in the univariate but not the multivariate analyses (Metindir and Dilek, 2009).In the study by Gorelick et al. (2009) fourteen of 66 patients (18.2%) exhibited thrombocytosis and patients with advanced disease had a significant higher mean preoperative platelet count compared with patients with localized disease.However, preoperative thrombocytosis was an independent prognostic factor only in patients with advanced endometrial cancer.Among patients with early-stage disease, preoperative thrombocytosis was not associated with worsened PFS or OS (Gorelick et al., 2009).Our present data support the previous studies involving patients with endometrial cancer that thrombocytosis prior to surgery is associated with other poor prognostic factors.However, in term of disease-free survival and overall survival, the presence of thrombocytosis is shown to be a prognostic factor in the univariate but not the multivariate analyses.

Table 4 . Multivariate Analysis for Overall Survival
et al. found a significant correlation