A Comparative Study Of Locally Advanced Esophageal Squamous Cell Carcinoma Between Involved-node Radiotherapy And Involved-field Radiotherapy

Backgrounds:Esophageal carcinoma is the eighth most common cancer and rank the sixth leading cause of cancer mortality worldwide.Oesophageal cancer is one of the deadliest cancers in China.Concurrent chemoradiotherapy(CCRT)has already been established as a standard therapeutic option for patients with locally advanced esophageal cancer.And it has been shown that chemoradiotherapy improved the local control rate and overall survival.With the development of medical imaging and computer technology,radiotherapy has access to the age of precise radiotherapy and achieved the accurate shooting.In the three-dimensional conformal radiotherapy(3D-CRT),it is primary and basic to define the target area accurately.Meanwhile,keeping high accuracy is one of the important factors increasing the local control rate.That is a question how to achieve the reasonable distribution of radiation dose-the target area accepts high dose,while normal tissue organs outside the target area are significantly lower.However,there is no clear consensus on the definition of the clinical target volume.Purpose:The retrospective study was to investigate the optimal clinical target voliune for radiotherapy of esophageal squamous cell carcinoma(ESCC)by comparing the local control rate,survival rate,the failure model and toxicity between involved-field radiotherapy(IFRT)and involved-node radiotherapy(INRT).Methods:A total of 151 patients with locally advanced esophageal squamous cell carcinoma received CCRT were included in the study between January 2010 and December 2014.According to the irradiation volume,the patients were allocated into either the IFRT group or the INRT group.We assessed progression-free survival(PFS),overall survival(OS)?the first site of disease relapse and treatment-related toxicity between the two groups.According to the relationship between disease progression and radiation target volume,the failures were segregated into in-INRT-fiela(a local field),out-INRT-in-IFRT-field(a regional field)and out-IFRT-field(other nodal and distant field)recurrences.And we further analyzed the survival of patients with specific pattern.Comparisons of the baseline characteristics and site of first failure were performed with x2 tests or Wilcoxon Rank Sum tests.Categorical variables were tabulated by frequency and percentage.The Kaplan-Meier methods were used to estimate these endpoints.The log-rank test was used to test the distribution of survival time between arms.Student’s t-test was used for comparison of means.Fisher’s exact test was used for comparisons of categorical data.By the proportional hazard model,the univariate and multivariate analysis was performed to address such confounding factors as age,gender,TNM stage,nodal status,tumor length,location of primary tumor,and the site of first failure with RT field of INRT versus IFRT on PFS and OS.For treatment toxicity,the Kruskal-Wallis H test was applied.The level of significance was set as p<0.05.Results:At a median tollow-up of 41 months(range 2-63 months),the median OS was 27 months for INRT group and 31 months for IFRT group(P = 0.656).In the INRT arm,the 1-,2-,3-,and 4-year OS rates were 76.9%,64.6%,30.8%,and 12.3%,respectively,versus 86.0%,72.1%,34.9%,and 13.4%in the IFRT arm.There was no difference between the two groups,(P = 0.656).The most common site of local failure was in-field for both groups.Meanwhile,in the univariate and multivariate analysis,the different RT fields were no associated with the PFS and OS.It had also showed that the most toxicities were esophagus or lung related toxicity caused by radiotherapy and hematologic toxicities caused by chemotherapies.No severe hematologic toxicity and pneumonia was observed in two arms.By stratified analysis,regarding to the acute and late toxicities,it was discovered that esophagus,lung and hematologic toxicity including infection no reached a statistical significance for the INRT versus the IFRT arm.(p≥0.05)Conclusions:Our results suggested that INRT could be a possible better treatment option than IFRT for ESCC with similar prognosis and acceptable adverse effect.Compared with IFRT,INRT does not sacrifice OS or PFS,the in-field failure has major effect on survival.In summary,INRT is feasible for patients with EC,the incidence of isolated regional lymph node recurrences was also acceptable.INRT can result in reduced incidences of treatment toxicities,enabling more patients to tolerate CCRT.