Validation of the Japanese Version of the Functional Assessment of Cancer Therapy-Cognitive Function Version 3

Cancer therapy-induced cognitive impairment adversely affects the quality of life of patients with cancer but cannot be detected by neuropsychological tests.

This study aimed to validate a Japanese version of the Functional Assessment of Cancer Therapy-Cognitive Function (FACT-Cog) version 3, which is a self-report measure of the cognitive concerns of patients with cancer.

The FACT-Cog was translated into Japanese and pilot tested with five patients with breast cancer and five patients with hematologic malignancy. Study participants were recruited in Hiroshima University Hospital and Kagawa Breast Clinic in Hiroshima, Japan. Patients with breast cancer (N = 236) responded to the resultant assessment and Functional Assessment of Cancer Therapy-General version 4. The internal consistency and concurrent and construct validity of the FACT-Cog were examined.

The Cronbach's alphas of the four FACT-Cog subscales, namely, CogPCI, CogOth, CogPCA, and CogQOL, were 0.95, 0.73, 0.93, and 0.88, respectively. The item-to-domain correlations ranged from 0.211 to 0.920. Most of the FACT-Cog subscales were significantly correlated with other subscale and total scores (r = 0.133-0.425). Structural equation modeling was barely acceptable (χ2 = 1361.8, df = 489, P < 0.001; goodness of fit index = 0.731, adjusted goodness of fit index = 0.691, comparative fit index = 0.848, root-mean-square error of approximation = 0.087).

The Japanese version of the FACT-Cog is a valid and reliable self-report measure of the cognitive function of patients with breast cancer. Its utility to clinicians and researchers in measuring the cognitive concerns of patients with cancer in Japan will serve as a further test of its validity.