Dear Editor

We recently reviewed the meta-analysis Liao et al. conducted [1]. The authors pooled and analyzed the effect of previous transurethral resection of the prostate (TURP) on radical prostatectomy based on 13 studies. It deals with an important clinical issue. However, we think that there are some issues may need to be reconsidered.

Firstly, this meta-analysis was not registered, it was required that “Every research study involving human subjects must be registered” by the World Medical Association’s Declaration of Helsinki 2013 states [2]. Secondly, the authors declared that they did a meta-analysis to compare radical prostatectomy between previous TURP group and non-TURP group. However, we found that the research Colombo [3] did was about TURP and open prostatectomy. Also, the research Yazici [4] did was about previous surgery for bladder outlet obstruction. Both researches are not confined to TURP. So, the author’s topic is not clear. Thirdly, the authors did not include all the researches in this meta without reasons. For example, the researchers Fragkoulis [5], Pastore [6] and Ramirez Backhaus [7] did. Finally, this meta-analysis compared the oncological outcome without comparing the stage grade and other parameters in the cohort. For example, positive surgical margin rate particularly is dependent upon patient and disease factors like Gleason grade, Apical tissue biopsy status and the quality of pathological evaluation.