Tumor resection reduced circulating tumor cell dissemination

Background: Cancer is a major public health problem worldwide. Whether to perform tumor resection or non-resection remains controversial face different types. Circulating tumor cells (CTCs) which are classified into three subpopulations epithelial (E-CTC), mesenchymal (M-CTC), and epithelial mesenchymal (E/M-CTC) based on expression of specificity biomarker. Methods: We identified CTCs using CanPatrol CTC enrichment technique from peripheral blood samples of 930 patients with tumor resection or non-resection. Patients were divided into two groups: Resection (n=615) and Non-resection (n=315). The relationship between tumor resection and count of CTCs were studied by using correlation analysis. Results: The mean patient age was 57.52 years (range, 17–87 years). Univariate analysis tumor resection could significantly reduce the number of total CTC cells (hazard ratioHR, 0.92, 95% confidence interval, CI= 0.903-0.937; P < 0.001), the E-CTC cells (HR, 0.889, 95% CI= 0.837-0.944; P < 0.001), the M-CTC cells (HR, 0.799, 95% CI= 0.735-0.869; P < 0.001), and the E/M-CTC cells (HR, 0.908, 95% CI= 0.888-0.928; P < 0.001).Furthermore, correlation analysis between total CTC and E-CTC, M-CTC, and E/M-CTC, the pearson correlation coefficient was 0.467, 0.458, and 0.963, respectively. Conclusions: In conclusionthe tumor resection can reduce the number of CTCs in peripheral blood. Reducing CTCs may serve as marker for prediction of prognosis, including tumor recurrence, metastasis and survival.


Background
Cancer is the second leading cause of death in the United States and is a major public health problem worldwide. The latest study suggest that the continuous decline in cancer death rates since 1991 has resulted in an overall drop of 27%, and the cancer incidence rate (2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) was stable in women and declined by nearly 2% per year in men during the past decade in the United States [1]. However, in large number of countries these incidences continue to rise [2]. Treatment of tumor metastases are an extremely important clinical issue worldwide since standardized early detection have developed and brought to an earlier detection and diagnosed cases in early stage of tumor [3].While surgery resection can be effective curative method in carefully selected patients in tumor metastases [4]. The circulating tumor cells (CTCs) into the blood stream gradually proven to have great clinical potential 3 for better prognosis in post-resection.
The CTCs originating from solid tumors, shed from primary and metastasized tumors, and other unidentified sites, into the blood stream [5]. CTCs can enhance tumor cell invasion and proliferation via undergoing epithelial-mesenchymal transition (EMT) [6]. According to the specific marker expression, the CTCs can now be divided into the epithelial (E-CTCs), mesenchymal (M-CTCs), and epithelial mesenchymal (E/M-CTCs) types. And the M-CTCs have been reported to positive correlation with more serious risk of recurrence in hepatocellular carcinoma [7,8], non-small cell lung cancer [9], and prostate cancer [10] et al. Due to their abundant presence, and previous studies have shown that CTCs count is related to poor prognosis in many metastatic cancers. However, the relationship between CTCs count with tumor resection and non-resection remains unclear. The aim of this study was to determine the CTCs types and count in solid tumors after resection.

Treatment options for patient selection
This prospective study was conducted at the first hospital affiliated to army medical university

4
The accuracy and the procedure of the CanPatrol system for isolating CTCs have been described previously. Briefly, blood was collected 1 to 2 days before resection. Peripheral blood samples (10 mL, anticoagulated with EDTA). Subsequently, the red blood cell were removed with RBC lysis buffer, then filtered through a filtration system with 8μm pore-size nano membrane (Millipore, Billerica, USA).The trapped CTCs were incubated with specific probes targeting epithelial (EpCAM, CK8, CK18 and CK19), mesenchymal (Vimentin and Twist) markers and anti-leukocyte CD45, in an automatic nucleic acid hybridization apparatus (SurExam, Guangzhou, China). After counterstaining with DAPI the CTCs were counted.

Statistical analysis
Either the chi squared test or Fisher's exact test was used, as appropriate, to analyze any correlation between the two groups. Data were presented as mean ± standard deviation (SD)The statistical analyses were performed using SPSS for windows (SPSS version 11.5, SPSS Inc., Chicago, IL) and GraphPad Prism (GraphPad Software Inc., San Diego, CA, USA). Unpaired Student's t-Test was used to analyze the statistical significant between two groups, respectively. And P values less than 0.05 were considered statistically significant.

Patients characteristics
A total of 930 patients (584 males and 346 females) with complete data during were enrolled in this study with different tumor types showing in Table 1. The mean patients age was 57.52 years (range, 17-87 years). All patients were divided into two groups the resection group (n=315, male 200, female 115) and the non-resection group (n=615, male384, female 231). The baseline characteristics of the 930 patients are listed in Table 2.
All three subtypes of CTCs were isolated E-CTCs, M-CTCs, and E/M-CTCs were detected in peripheral blood samples of the patients which after resection or before non-resection, respectively. The clinicopathological characteristics of the all patients, demarcated by the CTCs subtypes, were counted. Table 3 shows that the peripheral blood total CTCs counts ranged from 0 to 181 (mean ± standard deviation, 14.72 ± 18.239), E-CTCs counts ranged from 0 to 40 (1.82 ± 3.58), M-CTCs 5 counts ranged from 0 to 26 (1.65 ± 2.663), E/M-CTCs counts ranged from 0 to 176 (11.26 ± 16.011).

CTC counts are associated with tumor resection
Univariate analysis of factors influencing all types of CTCs after tumor resection or non-resection.
Patients who were underwent tumor resection could significantly reduce the number of total CTCs

Discussion
Currently, CTCs have attracted tremendous attention because of the minimally invasive approaches applied to obtain sequential blood specimens from cancer patients and their potential clinical implications [11]. Hence, CTC counts in peripheral blood as important clinical parameters in preoperative, perioperative, postoperative for new diagnostic and predict risk of cancer metastasis. In addition, CTCs are released from the primary tumor into the bloodstream and have the potential to spread to distant sites and develop into micrometastasis [12]. Although, previous studies have demonstrated that CTCs count is not correlation to tumor node metastasis staging and the high CTCs count was negative prognostic factor [15] and CTCs number in patients with non-small cell lung cancer has not find a correlation between CTCs count and disease stage [16].
On the other hand, in a study showed that CTCs count was higher in non-small cell lung cancer patients with later stage [18]. The CTCs positive in hepatocellular carcinoma (HCC) patients after liver resection has a significantly higher risk of recurrence compared to those who were CTCs negative, 6 and the concept of CTCs being potential seeds of metastatic dissemination [17]. There are studies demonstrated that the surgical resection may increase the dissemination of tumor cells into the circulation [13,14]. So, it is critical to know CTCs counts into the blood stream that dissemination from the primary tumor through surgical intervention to predict recurrence and metastasis, or judgement if chemotherapy is necessary after surgical treatment.
In this study, we compared with surgical tumor resection and non-resection to establish the relationship between CTCs counts between tumor surgery and not. We used the CanPatrolTM CTC

Ethics approval and consent to participate
The study was approved by Ethics Committees/Institutional Review boards at all participating southwest hospital, third military medical university. Written consent was obtained from all patients prior to participating in the study.

Consent for publication
Consent for publication was obtained from included participants.