Previous research revealed associations of ABCB1 transcript levels with poor outcomes in ovarian cancer (Johnatty et al. 2013; Sun et al. 2016), gastric cancer (Oliveira et al. 2014) and HCC (Fan et al. 2016), whereas inverse trends have been reported for HNSCC (Warta et al. 2014) and ccRCC (Reustle et al. 2018). This evidence concerns the gene ABCB1 and ovarian cancer.