Patterns Of Local Recurrence In Rectal Cancer After Tme And Implication In Delineation Of Clinical Target Volume For Radiation Therapy

Objective : The characteristics of locoregional rectal cancer recurrences following total mesorectal excision(TME)were not clear in past years.We tried to analyze it in this passage and help to suggest the optimal radiotherapy clinical target volume.Methods:The clinical materials of 134 patients who had recurrence and metastasis following TME without radiotherapy between January 2012 and November 2018 in our hospital were retrospectively analyzed.Chi-square test was used to evaluate the relationship between lymph node metastasis and clinicopathological factors,such as the location of primary tumors and the stage.Also,the correlation between different lymphatic drainage of rectal cancer was tested.Results:In total,134 patients were enrolled in this study.The median time to relapse was 15 months.The incidences of anastomotic,rectum and mesorectal,pelvic presacral space,abdominal presacral space,internal iliac nodes,external iliac nodes,obturator nodes,inguinal nodes,ischiorectalfossa were 42.5%(57/134),26.9%(36/134),25.4%(34/134),7.5%(10/134),34.3%(46/134),3.7%(5/134),0.7%(1/134),9.7%(13/134),8.2%(11/134).Compared with mid-lower rectal cancer,upper rectal cancer was more prone to metastasis in the abdominal presacral space(19.0% vs.5.6%,P=0.028).Patients with inguinal lymph node metastasis were more likely to be found with external iliac nodes metastasis(23.1% vs.1.7%,P=0.006).Conclusions : There is a great difference in lymphatic drainage of metastasis between the upper and mid-lower rectal cancer.As a result,the clinical target volume of radiation therapy for upper and mid-lower rectal cancer should be defined separately.It’s of great value to optimize the clinical target volume of radiotherapy in future.