Cognitive deterioration determined by the HVLT-R at three or four months was employed as a primary endpoint in two randomized clinical trials (RCTs) comparing SRS alone and SRS + WBRT for patients with one to three brain metastases . In a recent publication from North America, Brown et al. reported that there was less cognitive deterioration at three months after SRS alone (40/63, 63.5%) than when SRS was combined with WBRT (44/48, 91.7%). In a smaller RCT from the MD Anderson Cancer Center, Chang et al. reported that patients who were randomly assigned to receive SRS + WBRT were significantly more likely to show a decline in learning and memory function (mean posterior probability of decline 52%) at four months than patients assigned to receive SRS alone (mean posterior probability of decline 24%). It should be noted that the former (Brown et al.) study recruited 213 patients (SRS alone, n = 111, SRS + WBRT, n = 102); however, only 57% (63/111) of the patients in the SRS-alone group and 47% (48/102) of the patients in the SRS + WBRT group underwent HVLT-R at three months. Similarly, in the Chang et al. study, only 67% (20/30) of the patients in the SRS-alone group and 39% (11/28) of the patients in the SRS + WBRT group underwent the HVLT-R at four months. The results of the present study suggest that the four-month decline in NCF is characteristic of the lower-KPS group, and this early decline must be distinguished from the true long-term toxicities that affect the favorable-prognosis group. This finding is supported by the RTOG 0933 trial evaluating hippocampus-avoiding WBRT; Gondi et al. reported that the HVLT-R DR scores of the patients who had died by six months declined significantly over time . This decline was not observed in the patients who were alive at six months.