The purpose of this study was to investigate the validity and reliability of the Japanese version of the Peace, Equanimity, and Acceptance in the Cancer Experience questionnaire (PEACE-J) and to evaluate the association between the PEACE subscales and Japanese patient characteristics.

A cross-sectional web-based survey was conducted among 412 patients with cancer. This survey assessed medical and demographic factors, such as the PEACE, the Coping Inventory for Stressful Situations (CISS), and the Functional Assessment of Chronic Illness Therapy — Spiritual well-being (FACIT-Sp). The forward–backward translation method was used to develop the PEACE-J. The validity of PEACE-J was evaluated by exploratory and confirmatory factor analysis, and correlation analysis between each subscale of PEACE and FACIT-Sp and CISS. The Cronbach's α and the item-total correlation of each subscale of the PEACE questionnaire were calculated to assess internal consistency reliability.

The factor analysis yielded two subscales corresponding to the original version: Cronbach's α coefficients were 0.84 and 0.86 for the Peaceful Acceptance of Illness subscale and the Struggle with Illness subscale, respectively. The PEACE subscales and the FACIT-Sp subscales and the CISS subscales were moderately associated with each other, including the Peaceful Acceptance to each subscale of FACIT (r = 0.22–0.55, p < 0.01); and the Peaceful Acceptance and the Struggle with Illness to CISS emotion-oriented coping (r = −0.36 and r = 0.45, p < 0.01, respectively). Married patients showed higher levels of peaceful acceptance than unmarried patients (p < 0.001). Poorer performance status, chemotherapy use, and recurrence or metastasis were significantly associated with higher levels of struggle with illness (p < 0.001).

This study indicated that the PEACE-J is a valid and reliable measure of the patient's sense of acceptance, calmness or equanimity, and peace, as well as their sense of struggle or desperation concerning their illness.