A114: Correlation between MRI detected extra-mural vascular invasion in rectal cancer and metastatic disease: a meta-analysis
1Croydon University Hospital, Croydon, UK,2Royal Marsden Hospital, Surrey, UK,3Royal Marsden Hospital, Chelsea, UK
Extramural vascular invasion (EMVI) is an independent prognostic factor in rectal cancer. Whilst traditionally it has been detected on histopathology analysis of the surgical resection specimen, more recently, it has been readily identified on magnetic resonance imaging (MRI), which can aid in pre-operative decision-making. The aim of this article is to meta-analyse the literature to ascertain the prevalence of rectal tumours with extramural vascular invasion and its association with synchronous and risk of developing metachronous metastatic disease after surgery.
Electronic databases were searched from January 1950 to March 2015. Data was extracted and combined using Comprehensive MetaAnalysis
Five articles reported on EMVI in 1194 patients. There were 364 patients in the EMVI positive group and 830 patients in the EMVI negative group. The combined incidence of EMVI positive tumours was 0.313 (Range=0.198-0.527). Patients who had EMVI positive tumours had more metastases at presentation compared with EMVI negative tumours [fixed effects model: RR=5.68,95%CI(3.75,8.61),z=8.21,df=2,p<0.001]. Patients who had EMVI positive tumours had more metastases during follow-up compared with EMVI negative tumours [random effects model: RR=2.57,95%CI(1.70,3.88),z=4.46,df=4,p<0.001].
MRI-detected EMVI (mrEMVI) is an independent prognostic factor with a significant prevalence in rectal tumour population. Synchronous metastases are over five times more likely when EMVI is present and patients are over twice as likely to develop metastases after surgery.