One of the interesting findings of the present study is that a significant decline in the score at four months was observed only in the patients who underwent the examination twice (worse-prognosis group; baseline and four months) but not in the patients who underwent the examination three times (better-prognosis group; baseline, four, and eight months). Sixteen (36%) of our patients underwent the four-month HVLT-R but dropped out before the eight-month examination. Their DR scores declined significantly compared to the baseline, and they were also significantly more likely to have declined individual TR and DR scores at four months compared to the patients who completed the four-month examination. The reason for dropping out by eight months was mostly death from cancer or worsened general condition. The KPS ≤ 70 at the baseline was a risk factor for discontinuation of the HVLT-R and declined individual TR scores at four months. The KPS is regarded as a prognostic factor of several primary cancer sites, and it is reasonable that the patients with a low KPS have worse survival and cannot undergo repeated HVLT-R examinations.