Since no studies have been reported that evaluated FDG PET-CT imagings in patients who were treated with cancer vaccine therapy, we performed a retrospective analysis of the findings of the FDG PET-CT imagings for patients who had been enrolled in our previous clinical studies using Wilms Tumor 1 (WT1) vaccine therapy.[7–11] In these clinical studies, WT1 vaccine therapy had been performed for cancer patients who had residual cancer lesion or high risk of relapse after initial therapy,[9–12] and PET-CT imagings were taken to assess the residual tumor. This evidence concerns the gene WT1 and cancer.