Objective To study the characteristics of microscopic spread of esophageal squamous-cell carcinoma (ESCC) and the influence of clinicopathological features on it to help define the clinical target volume (CTV) margin in radiotherapy.Methods Sixty-four surgical specimens of ESCC were observed for longitudinal microscopic spread per centimeter both proximally and distally from the tumor.The shrinkage ratio of each specimen was calculated and used for tissue incision.Results The further the distance beyond the tumor, the lower the incidence there was of microscopic spread.Positive rates of microscopic spread in group 3 cm of proximal and distal were 4.8% and 6.9%, respectively, and in group 4 cm were both 3.6%.Tumors longer than 5 cm in length,with poorer differentiation, lymph nodes metastasis and more aggressive phase had higher positive rates (79.3% vs 45.7%,77.4% vs 45.5%,76.0% vs 51.2%,70.5% vs 40.0%,χ2=7.52,6.86,3.91,5.36;P=0.006,0.009,0.042,0.021).Differentiation and tumor length were main factors contributing to microscopic spread (χ2=0.19,4.82;P=0.020,0.017).Conclusions To cover 95% of the microscopic spread,a margin of 3.0 cm proximal and 4.0 cm distal beyond gross tumor volume is needed and as to 90%, a margin of 3.0 cm both proximal and distal is needed.Moreover, the influence of pathological features should be taken into account.

Mitochondrial fission regulator 2 (MTFR2) is associated with mitochondrial fission, while few studies have assessed the associations between MTFR2 expression and clinical characteristics or prognosis of esophageal squamous cell carcinoma (ESCC). In this study, we compared the expression of MTFR2 in 6 ESCC tumors and relative normal tissues by immunohistochemistry (IHC). To assess the effect of MTFR2 expression on clinicopathologic characteristics and survival, 115 paraffin embedded ESCC tissue samples were assessed by IHC staining. Furthermore, the association between clinicopathological properties and MTFR2 expression in patients with ESCC was examined. The survival analysis was performed using the Cox regression models. We found that MTFR2 expression was significantly increased in ESCC tumors compared with normal esophageal epithelial cells. IHC analysis of 115 paraffin embedded ESCC tumor specimens of the patients showed that the expression of MTFR2 was significantly associated with clinical stage (P < 0.001), tumor classification (P < 0.001), histological grade (P < 0.001), and other clinicopathological characteristics. Both univariate and multivariate analyses showed that MTFR2 expression was inversely correlated with the survival of ESCC patients. In conclusion, the expression of MTFR2 is significantly associated with clinicopathologic characteristics and prognosis of ESCC. Thus, MTFR2 expression could serve as a potentially important prognostic biomarker and clinical target for patients with ESCC.