Metastases-directed stereotactic body radiotherapy in combination with targeted therapy or immunotherapy: systematic review and consensus recommendations by the EORTC-ESTRO OligoCare consortium.

Stereotactic body radiotherapy (SBRT) for patients with metastatic cancer, especially when characterised by a low tumour burden (ie, oligometastatic disease), receiving targeted therapy or immunotherapy has become a frequently practised and guideline-supported treatment strategy. Despite the increasing use in routine clinical practice, there is little information on the safety of combining SBRT with modern targeted therapy or immunotherapy and a paucity of high-level evidence to guide clinical management. A systematic literature review was performed to identify the toxicity profiles of combined metastases-directed SBRT and targeted therapy or immunotherapy. These results served as the basis for an international Delphi consensus process among 28 interdisciplinary experts who are members of the European Society for Radiotherapy and Oncology (ESTRO) and European Organisation for Research and Treatment of Cancer (EORTC) OligoCare consortium. Consensus was sought about risk mitigation strategies of metastases-directed SBRT combined with targeted therapy or immunotherapy; a potential need for and length of interruption to targeted therapy or immunotherapy around SBRT delivery; and potential adaptations of radiation dose and fractionation. Results of this systematic review and consensus process compile the best available evidence for safe combination of metastases-directed SBRT and targeted therapy or immunotherapy for patients with metastatic or oligometastatic cancer and aim to guide today's clinical practice and the design of future clinical trials.

Medical Oncology Education in Europe: Equipping Medical Oncologists to Provide the Best Care for Patients with Cancer.

BACKGROUND: High-quality, evidence-based, and practice-relevant education is essential to equip medical oncologists to provide high-quality care for patients with cancer. The need for medical oncology education is growing due to a rapid development of new therapies with novel mechanisms of action. Moreover, the number of patients with cancer is increasing with the rising in incidence and improved survival for some cancers. Access to medical oncology education and training opportunities, particularly in research, varies considerably in different countries and regions. SUMMARY: The European Society for Medical Oncology (ESMO), the European School of Oncology (ESO), and other relevant associations have developed a wide range of opportunities, resources, and measures to increase access to high-quality medical oncology education. Initiatives that are helping to achieve effective and consistent medical oncology education include the ESMO/ASCO (American Society of Medical Oncology) global curriculum in medical oncology. KEY MESSAGES: There is great value in providing wider educational opportunities than local and national training to increase access and, potentially, quality and scope and reduce variations in medical oncology education. Pan-European and global educational initiatives open up the expertise, knowledge, and best practice on different tumour types and cross-sectional topics, such as supportive and palliative care that can be shared between medical oncologists from other countries.

Automated enumeration and phenotypic characterization of CTCs and tdEVs in patients with metastatic castration resistant prostate cancer.

BACKGROUND: Although most patients with metastatic castration-resistant prostate cancer (mCRPC) initially benefit from treatment with androgen receptor signaling inhibitors (ARSi), resistance inevitably occurs. Hence, we investigated the prognostic value of automated circulating tumor cell (CTC) and tumor-derived extracellular vesicle (tdEV) enumeration and their dynamics, in patients with mCRPC in the context of the initiation of treatment with ARSi. Furthermore, we hypothesize that CTC phenotypic heterogeneity might serve as a measurable biomarker under these circumstances. METHODS: Using an image analysis tool, we reanalyzed all CellSearch images previously acquired in the context of a prospective, multicenter clinical study for patients with mCRPC (n = 170) starting a new line of ARSi, for CTC and tdEV detection and enumeration. CTC (n = 19 129) phenotypic diversity was quantified by the Shannon index (SI). Progression-free survival (PFS) and overall survival (OS) were compared between groups of patients stratified according to CTC, tdEV, and SI levels. RESULTS: Automated CTC enumeration provided similar clinical prognostication compared with operator-based counts. Patients demonstrating high CTC phenotypic heterogeneity before therapy had a shorter median PFS (4.82 vs. 8.49 months, HR 1.79; P = 0.03) and OS (12.6 months vs. not reached, HR 2.32; P = 0.03), compared to patients with low diversity, irrespective of CTC level. Multivariable analysis showed how the prognostic value of the baseline SI was lost by pretreatment chemotherapy status, CTC counts, and PSA levels. CONCLUSIONS: Automated CTC counts are a reliable substitute for reviewer-based enumeration, as they are equally informative for prognosis assessment in patients with mCRPC. Beyond enumeration, we demonstrated the added value of studying CTC phenotypic diversity for patient prognostication, warranting future investigation.

Oncological outcome, postoperative complications, and mammographic changes after intraoperative radiotherapy with electrons (IOERT) as a boost in a large single-institution cohort of breast cancer patients.

Advantages of using intraoperative radiotherapy with electrons (IOERT) as a boosting modality in breast-conserving therapy include the direct visualization of the tumor bed, a reduced skin dose, and patient convenience. We report oncological outcome, postoperative complication rate, and mammographic changes on follow-up imaging in women treated at our institution with IOERT as a boost modality in breast-conserving therapy for early-stage breast carcinoma. Between January 2007 and June 2018, 763 consecutive patients were enrolled. During breast-conserving surgery, an IOERT boost of 9 Gy was applied, followed by whole breast irradiation (WBI). At a median follow-up of 62.2 months (range: 0.5-135), 13 in-breast recurrences were observed, yielding a local tumor control rate of 98.4% at 5 years. In multivariable analysis, high tumor grading was predictive for local recurrence (HR = 5.6; 95%CI: 1.19-26.2). A total of 27 (3.5%) patients developed any kind of postoperative complication. None of the tumor characteristics nor any of the IOERT technical parameters were predictive for development of a postoperative complication. On follow-up imaging, 145 patients with mammographic changes BIRADS score ≥3 were found of which 50.3% required a biopsy. Only 17 patients had positive biopsies; none of the IOERT parameters were predictive for false-positive imaging. A 9 Gy IOERT boost combined with postoperative WBI provided outstanding local control rates, was well-tolerated, with limited postoperative complications. However, radiologists must be aware of a presumable higher prevalence of mammographic changes after IORT as a boost.

Phase II open-label study investigating apalutamide in patients with biochemical progression after radical prostatectomy.

Apalutamide, a competent inhibitor of the androgen receptor, has shown promising clinical efficacy results for patients with advanced prostate cancer. Here, we describe the rationale and design for the SAVE trial, a multi-center, Phase II study, wherein 202 men with biochemical progression after radical prostatectomy are randomly assigned 1:1 to apalutamide plus salvage radiotherapy (SRT) or androgen-deprivation therapy with an luteinizing hormone-releasing hormone agonist or antagonist plus SRT. The primary objective is to compare sexual function between the two treatment arms based on the expanded prostate cancer index-26 sexual domain score at nine months after start of hormonal treatment. The key secondary objectives are to assess quality of life, to evaluate the safety profile and the short-term efficacy of apalutamide in combination with SRT. ClinicalTrials.gov identifier: NCT03899077.

TP53 Outperforms Other Androgen Receptor Biomarkers to Predict Abiraterone or Enzalutamide Outcome in Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: To infer the prognostic value of simultaneous androgen receptor (AR) and TP53 profiling in liquid biopsies from patients with metastatic castration-resistant prostate cancer (mCRPC) starting a new line of AR signaling inhibitors (ARSi).Experimental Design: Between March 2014 and April 2017, we recruited patients with mCRPC (n = 168) prior to ARSi in a cohort study encompassing 10 European centers. Blood samples were collected for comprehensive profiling of CellSearch-enriched circulating tumor cells (CTC) and circulating tumor DNA (ctDNA). Targeted CTC RNA sequencing (RNA-seq) allowed the detection of eight AR splice variants (ARV). Low-pass whole-genome and targeted gene-body sequencing of AR and TP53 was applied to identify amplifications, loss of heterozygosity, mutations, and structural rearrangements in ctDNA. Clinical or radiologic progression-free survival (PFS) was estimated by Kaplan-Meier analysis, and independent associations were determined using multivariable Cox regression models. RESULTS: Overall, no single AR perturbation remained associated with adverse prognosis after multivariable analysis. Instead, tumor burden estimates (CTC counts, ctDNA fraction, and visceral metastases) were significantly associated with PFS. TP53 inactivation harbored independent prognostic value [HR 1.88; 95% confidence interval (CI), 1.18-3.00; P = 0.008], and outperformed ARV expression and detection of genomic AR alterations. Using Cox coefficient analysis of clinical parameters and TP53 status, we identified three prognostic groups with differing PFS estimates (median, 14.7 vs. 7.51 vs. 2.62 months; P < 0.0001), which was validated in an independent mCRPC cohort (n = 202) starting first-line ARSi (median, 14.3 vs. 6.39 vs. 2.23 months; P < 0.0001). CONCLUSIONS: In an all-comer cohort, tumor burden estimates and TP53 outperform any AR perturbation to infer prognosis.See related commentary by Rebello et al., p. 1699.

Cell-free DNA profiling of metastatic prostate cancer reveals microsatellite instability, structural rearrangements and clonal hematopoiesis.

BACKGROUND: There are multiple existing and emerging therapeutic avenues for metastatic prostate cancer, with a common denominator, which is the need for predictive biomarkers. Circulating tumor DNA (ctDNA) has the potential to cost-efficiently accelerate precision medicine trials to improve clinical efficacy and diminish costs and toxicity. However, comprehensive ctDNA profiling in metastatic prostate cancer to date has been limited. METHODS: A combination of targeted and low-pass whole genome sequencing was performed on plasma cell-free DNA and matched white blood cell germline DNA in 364 blood samples from 217 metastatic prostate cancer patients. RESULTS: ctDNA was detected in 85.9% of baseline samples, correlated to line of therapy and was mirrored by circulating tumor cell enumeration of synchronous blood samples. Comprehensive profiling of the androgen receptor (AR) revealed a continuous increase in the fraction of patients with intra-AR structural variation, from 15.4% during first-line metastatic castration-resistant prostate cancer therapy to 45.2% in fourth line, indicating a continuous evolution of AR during the course of the disease. Patients displayed frequent alterations in DNA repair deficiency genes (18.0%). Additionally, the microsatellite instability phenotype was identified in 3.81% of eligible samples (≥ 0.1 ctDNA fraction). Sequencing of non-repetitive intronic and exonic regions of PTEN, RB1, and TP53 detected biallelic inactivation in 47.5%, 20.3%, and 44.1% of samples with ≥ 0.2 ctDNA fraction, respectively. Only one patient carried a clonal high-impact variant without a detectable second hit. Intronic high-impact structural variation was twice as common as exonic mutations in PTEN and RB1. Finally, 14.6% of patients presented false positive variants due to clonal hematopoiesis, commonly ignored in commercially available assays. CONCLUSIONS: ctDNA profiles appear to mirror the genomic landscape of metastatic prostate cancer tissue and may cost-efficiently provide somatic information in clinical trials designed to identify predictive biomarkers. However, intronic sequencing of the interrogated tumor suppressors challenges the ubiquitous focus on coding regions and is vital, together with profiling of synchronous white blood cells, to minimize erroneous assignments which in turn may confound results and impede true associations in clinical trials.

Circulating tumor cells and survival in abiraterone- and enzalutamide-treated patients with castration-resistant prostate cancer.

BACKGROUND: The outcome to treatment administered to patients with metastatic castration-resistant prostate cancer (mCRPC) greatly differs between individuals, underlining the need for biomarkers guiding treatment decision making. OBJECTIVE: To investigate the prognostic value of circulating tumor cell (CTC) enumeration and dynamics, in the context of second-line endocrine therapies (ie, abiraterone acetate or enzalutamide), irrespective of prior systemic therapies. DESIGN, SETTINGS, AND PARTICIPANTS: In a prospective, multicentre study blood samples for CTC enumeration were collected from patients with mCRPC at baseline (n = 174). In patients who responded for minimally 10-12 weeks a follow-up sample was collected. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: For baseline analysis, patients were stratified in <5 or ≥5 CTCs/7.5 mL, whereas for the analysis of CTC dynamics at 10-12 weeks, in patients with stable, increasing or decreasing CTC counts. Progression-free survival (PFS), overall survival (OS), and PSA changes at 10-12 weeks were compared between groups. RESULTS: Patients demonstrating increasing CTCs on therapy had a shorter median PFS (4.03 vs 12.98 vs 13.67 months, HR 3.6, 95%CI 1.9-6.8; P < 0.0001) and OS (11.2 months vs not reached, HR 9.5, 95%CI 3.7-24; P < 0.0001), compared to patients with decreasing or stable CTCs. Multivariable Cox regression showed that prior chemotherapy (HR 4.1, 95%CI 1.9-8.9; P = 0.0003), a high baseline CTC count (HR 1.5, 95%CI 1.2-1.9; P = 0.002) and increasing CTCs at follow-up (HR 3.3, 95%CI 1.4-7.6; P = 0.005) were independent predictors of worse PFS. Previous chemotherapy (HR 7, 95%CI 1.9-25; P = 0.003), high baseline CTC counts (HR 2.2, 95%CI 1.4-3.7; P = 0.002) and increasing CTCs during therapy (HR 4.6, 95%CI 1.4-15; P = 0.01) were independently associated with shorter OS. ≥30% and ≥50% PSA responses less frequently occurred in patients with CTC inclines at 10-12 weeks on therapy (χ2 test: P < 0.01). CONCLUSIONS: CTC dynamics during therapy are associated with PSA response and provide independent clinical prognostication over PSA declines. Hence the study demonstrates the pharmacodynamic properties of CTCs.

Global cancer control: responding to the growing burden, rising costs and inequalities in access.

The cancer burden is rising globally, exerting significant strain on populations and health systems at all income levels. In May 2017, world governments made a commitment to further invest in cancer control as a public health priority, passing the World Health Assembly Resolution 70.12 on cancer prevention and control within an integrated approach. In this manuscript, the 2016 European Society for Medical Oncology Leadership Generation Programme participants propose a strategic framework that is in line with the 2017 WHO Cancer Resolution and consistent with the principle of universal health coverage, which ensures access to optimal cancer care for all people because health is a basic human right. The time for action is now to reduce barriers and provide the highest possible quality cancer care to everyone regardless of circumstance, precondition or geographic location. The national actions and the policy recommendations in this paper set forth the vision of its authors for the future of global cancer control at the national level, where the WHO Cancer Resolution must be implemented if we are to reduce the cancer burden, avoid unnecessary suffering and save as many lives as possible.

New treatment options for metastatic renal cell carcinoma.

During the last decade, the treatment of advanced or metastatic renal cell carcinoma (RCC) was revolutionised with the advent of antiangiogenic drugs and tyrosine-kinase inhibitors. Several agents targeting the vascular endothelial growth factor (VEGF) pathway (sunitinib, bevacizumab, pazopanib, axitinib) or the mammalian target of rapamycin pathway (temsirolimus, everolimus) were since then progressively approved for first-line or later-line use in the treatment of patients with advanced RCC and became the new standard of care. As a result, the survival of patients with advanced RCC has significantly improved from a median overall survival of approximately 12 months in the cytokines era to more than 26 months with first-line VEGF inhibitors. During the two last years, the treatment of advanced RCC has witnessed a second revolution with the advent of immune checkpoint inhibitors, especially agents targeting the programmed cell death-1 receptor, as well as with the advent of new generation tyrosine-kinase receptor inhibitors. This article will review the new therapeutic options available for the treatment of advanced RCC, as well as the future potential molecular targets that are currently being investigated.

Predictive and prognostic biomarkers of targeted agents and modern immunotherapy in renal cell carcinoma.

In the past decade, several agents targeting angiogenesis and signal transduction pathways have replaced the use of cytokines as standard of care treatment for metastatic renal cell carcinoma (RCC) after showing improved clinical benefit and survival. Currently, several novel immunotherapy agents targeting the programmed cell death-1 (PD-1) and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) pathways are being tested in metastatic RCC and are bound to revolutionise the management of this disease. However, the success of both antiangiogenic drugs and new immunotherapy agents still depends on our ability to select patients most likely to respond to treatment. This article will review the current available evidence on prognostic and predictive biomarkers of response to signal transduction pathways-targeted agents and modern immunotherapy in metastatic RCC.

Career opportunities and benefits for young oncologists in the European Society for Medical Oncology (ESMO).

The European Society for Medical Oncology (ESMO) is one of the leading societies of oncology professionals in the world. Approximately 30% of the 13 000 ESMO members are below the age of 40 and thus meet the society's definition of young oncologists (YOs). ESMO has identified the training and development of YOs as a priority and has therefore established a comprehensive career development programme. This includes a leadership development programme to help identify and develop the future leaders in oncology. Well-trained and highly motivated future generations of multidisciplinary oncologists are essential to ensure the optimal evolution of the field of oncology with the ultimate goal of providing the best possible care to patients with cancer. ESMO's career development portfolio is managed and continuously optimised by several dedicated committees composed of ESMO officers and is directly supervised by the ESMO Executive Board and the ESMO President. It offers unique resources for YOs at all stages of training and includes a broad variety of fellowship opportunities, educational courses, scientific meetings, publications and resources. In this article, we provide an overview of the activities and career development opportunities provided by ESMO to the next generation of oncologists.

Sarcomatoid dedifferentiation in metastatic clear cell renal cell carcinoma and outcome on treatment with anti-vascular endothelial growth factor receptor tyrosine kinase inhibitors: a retrospective analysis.

INTRODUCTION: This study aimed to assess the efficacy of anti-vascular endothelial growth factor receptor tyrosine kinase inhibitors (anti-VEGFR-TKIs) in patients with metastatic clear cell renal cell carcinoma (m-ccRCC) with sarcomatoid dedifferentiation. PATIENTS AND METHODS: The files of all patients with m-ccRCC consecutively treated with first-line anti-VEGFR-TKIs at the authors' institution were retrospectively reviewed. Pathology slides from nephrectomy and metastasectomy were assessed for the presence and extent of sarcomatoid dedifferentiation. RESULTS: A total of 124 patients were included; nephrectomy and metastasectomy specimens were available in 117 and 35 patients, respectively. Thirty percent of the primary nephrectomy specimens had sarcomatoid features, and the median involvement of the sarcomatoid component was 21% (range, 1%-95%). Patients with an important sarcomatoid component, defined as ≥ 25% involvement of the tumor, had a very poor outcome: progression-free survival (PFS) and overall survival (OS) were 3 and 6 months, respectively, and no partial responses (PR) were observed. Patients without sarcomatoid dedifferentiation or with sarcomatoid involvement < 25% had a PFS of 12 months (P < .0001; hazard ratio [HR], 51; 95% CI, 12.58-207.3), an OS of 22 months (P < .0001, HR, 10.72; 95% CI, 3.56-32.25), and a PR rate of 50% (P = .0015). Patients with a sarcomatoid component ≥ 25% in the metastasectomy also had a poorer PFS and OS on anti-VEGFR-TKIs compared with patients with < 25% of sarcomatoid features at these sites. CONCLUSION: Patients with m-ccRCC whose tumors contain a component of sarcomatoid dedifferentiation of ≥ 25% of the total tumor volume have a very poor outcome when treated with anti-VEGFR-TKIs. Analysis of the extent of sarcomatoid features in resected metastases can provide additional prognostic information.

Prognostic impact of baseline serum C-reactive protein in patients with metastatic renal cell carcinoma (RCC) treated with sunitinib.

OBJECTIVE: To evaluate the impact of baseline serum C-reactive protein (CRP) level on outcome in patients with metastatic renal cell carcinoma (mRCC) treated with sunitinib. PATIENTS AND METHODS: We reviewed the charts of patients with mRCC who started sunitinib as a first targeted treatment between 2005 and 2012 in three hospitals in Belgium and France. Collected data included known prognostic factors for mRCC, anatomical location of metastatic sites, response rate (RR), progression-free survival (PFS) and overall survival (OS). RESULTS: A total of 200 eligible patients were identified by retrospective chart review. The median PFS and OS were 12 and 20 months, respectively. We observed a clear impact of baseline CRP levels on outcome: the median PFS was 25 months in the group with baseline CRP ≤5 mg/L and 8 months in the group with baseline CRP >5 mg/L (hazard ratio [HR] 2.48, 95% CI 1.74-3.59). The median OS in each group was 50 vs 12 months, respectively (HR 3.17, 2.20-4.68). In the group with baseline CRP ≤5 mg/L, 61% of patients experienced a partial response compared with 32% of patients in the group with baseline CRP >5 mg/L (difference = 29%, 95% CI 15-42). When adding baseline CRP (with a log transformation) to the six variables of the International Metastatic RCC Database Consortium (IMDC) model in a multivariable Cox regression model, baseline CRP was independently associated with poor PFS (HR for each doubling in CRP level: 1.14, 95% CI 1.03-1.26; P = 0.01) and OS (HR: 1.29, 95% CI 1.16-1.43; P < 0.001). Adding baseline CRP to the model increased the c-statistic of PFS at 5 years from 0.63 (0.59-0.68) to 0.69 (0.65-0.73), and the c-statistic of OS at 5 years from 0.65 (0.60-0.69) to 0.70 (0.66-0.74). Patients with elevated baseline CRP levels had a poor prognosis independent of the IMDC risk group, whereas patients with a low baseline CRP in the IMDC favourable risk group had a very good outcome. CONCLUSION: Baseline serum CRP level is a strong independent variable linked with RR, PFS and OS in patients with mRCC treated with sunitinib.

External quality assurance of circulating tumor cell enumeration using the CellSearch(®) system: a feasibility study.

BACKGROUND: Circulating tumor cells (CTCs) are cells that have detached from solid tumors and entered the blood. CTCs can be detected, among others, by semi-automated immunomagnetic enrichment and image cytometry using CellSearch® (Veridex, Raritan, NJ). We studied the feasibility of external quality assurance (EQA) of the entire CellSearch procedure from blood draw to interpretation of results in multiple laboratories. METHODS: Blood samples from six cancer patients and controls were distributed to 14 independent laboratories to test between-laboratory, between-assay, and between-instrument variation. Additionally, between-operator variability was assessed through the interpretation of blinded images of all blood samples on a website. RESULTS: Shipment and storage of samples had no influence on CTC values. Between-instrument (coefficient of variation (CV) < 12%) and between-assay variation was low (CV ≤ 20%), indicating high reproducibility. However, between-laboratory CV ranged from 45 to 64%. Although inter-operator agreement on image interpretation (Fleiss' κ statistics) ranged from "substantial" to "almost perfect," image interpretation, particularly of samples containing high numbers of apoptotic cells, was the main contributor to between-laboratory variation. CONCLUSIONS: This multicenter study shows the feasibility of an EQA program for CTC detection in patient samples, and the importance of continuation of such a program for the harmonization of CTC enumeration.

mRNA levels of CD31, CD144, CD146 and von Willebrand factor do not serve as surrogate markers for circulating endothelial cells.

Circulating endothelial cells (CEC) are considered a promising marker to determine the extent of vascular damage. However, currently available and validated CEC enumeration assays are laborious, time consuming and costly, which limits their clinical utility. Here, we evaluated the feasibility of quantifying mRNA levels of the endothelium-associated markers CD31, CD144, CD146 and von Willebrand factor (vWf) in peripheral blood (PB) of healthy donors, patients, and human umbilical veins by real-time reverse transcriptase polymerase chain reaction (RT-PCR) and their use as surrogate markers for CEC. Whole blood samples and CD146+ cell-enriched fractions were assessed for mRNA and protein expression of CD31, CD144, CD146 and vWf by RT-PCR and flow cytometry, respectively. We showed the feasibility to detect endothelial mRNA isolated from HUVEC numbers as low as 10. However, no endothelial mRNA could be measure in whole blood samples, and only low levels of CD31 and CD146 mRNA were detected in suspensions of isolated CEC with numbers up to 4,450 CEC per sample. We conclude that mRNA levels of CD31, CD144, CD146 and vWf in whole blood as detected by real time RT-PCR cannot be used as biomarkers for end-stage endothelial cells such as CEC.

Levels of circulating endothelial cells in normotensive and severe preeclamptic pregnancies.

BACKGROUND: Preeclampsia is a disease hypothesized to originate from widespread endothelial dysfunction or damage. This study investigated whether circulating endothelial cells (CEC) can serve as a surrogate marker for disease severity in patients with preeclampsia, and if their number correlates to serum endothelial biomarkers for activation, dysfunction, or damage of those cells. METHODS: Blood was drawn consecutively from 30 patients admitted with a diagnosis of severe preeclampsia. Thirty healthy, normotensive, patients matched for age, body mass index, and gestational age served as a control group. We determined the number of CEC and serum concentrations of biomarkers indicative of endothelial damage (thrombomodulin) and activation (E-selectin), and the antiangiogenic protein (endoglin), which reflects endothelial dysfunction. RESULTS: Median CEC counts did not differ significantly between preeclamptic patients and the control group (median 5.3 vs. 3.5 CEC/mL, respectively) and were mostly within the normal range (i.e., <20 CEC/mL). However, serum concentrations of thrombomodulin (median 3.6 vs. 5.2 ng/mL; P = 0.006), E-selectin (median 32.0 vs. 42.9 ng/mL; P = 0.02), and especially endoglin (median 5.0 vs. 76.2 ng/mL; P < 0.0001) were significantly increased in severe preeclamptic patients. CEC counts did not correlate with any of the clinical parameters or routinely determined laboratory indices. CONCLUSION: Preeclampsia is characterized by endothelial dysfunction and activation rather than actual endothelial damage as characterized by increased CEC counts.