title: Tumor size and effectiveness of electrochemotherapy.
abstract: BACKGROUND
  Electrochemotherapy (ECT) is an effective and safe method for local treatment of tumors. However, relatively large variability in effectiveness of ECT has been observed, which likely results from different treatment conditions and tumor characteristics. The aim of this study was to investigate the relationship between tumor size and effectiveness of a single-session ECT.
  
  
  METHODS
  A systematic search of various bibliographic databases was performed and nine studies eligible for this study were extracted. Different statistical methods including meta-analysis were applied to analyze the data.
  
  
  RESULTS
  The results of analysis based on data from 1466 tumors of any histotype show significantly lower effectiveness of ECT on tumors with maximal diameter equal to or larger than 3 cm (complete response (CR) of 33.3%, objective response (OR) of 68.2%) in comparison to smaller tumors (CR% of 59.5%, OR% of 85.7%). The results of meta-analysis indicated that ECT performed on tumors smaller than 3 cm statistically significantly increases the probability of CR by 31.0% and OR by 24.9% on average in comparison to larger tumors. The analysis of raw data about the size and response of tumors showed statistically significant decrease in effectiveness of ECT progressively with increasing tumor diameter. The biggest drop in CR% was detected at tumor diameters as small as 2 cm.
  
  
  CONCLUSIONS
  The standard operating procedures for ECT should be reexamined and refined for the treatment of large tumors. We propose that future clinical trials should include accurate ECT treatment planning and/or multiple ECT cycles, besides a prolonged observation for tumor response evaluation.
authors: Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia.
authors: Barbara
authors: B
authors: Mali
authors: Damijan
authors: D
authors: Miklavcic
authors: Luca G
authors: LG
authors: Campana
authors: Maja
authors: M
authors: Cemazar
authors: Gregor
authors: G
authors: Sersa
authors: Marko
authors: M
authors: Snoj
authors: Tomaz
authors: T
authors: Jarm
keywords: cutaneous tumors; effectiveness; electrochemotherapy; meta-analysis; tumor size