Each patient’s NCF was assessed with the HVLT-R (Japanese version), consisting of the total recall (TR), delayed recall (DR), and delayed recognition (DRecog) subdomains. The HVLT-R was performed before (baseline) and at 4 months and 8 months after the completion of WBRT. The HVLT-R test battery contains six different question forms so that the participant cannot memorize the answers. The interval between the day exactly 4 or 8 months after WBRT and the actual date of the follow-up HVLT-R was <1 month. The HVLT-R scores were analyzed in two different ways. One way was an inter-group or intra-group (the baseline, 4, and 8 months) comparison of raw scores with nonparametric tests, and the other way was to judge whether the 4- or 8-month score of a participant was significantly declined compared to the baseline beyond a specific cutoff value. Significant deterioration in an individual’s NCF was defined as a drop from the baseline score by ≥5 points for TR, ≥3 points for DR, and ≥2 points for DRecog . For example, if the baseline TR score was 15 and the 8-month TR score was 9, the 8-month TR score was judged as declined compared to the baseline.