Аннотация:The current report provides the result of a Phase II clinical trial regarding the effectiveness and feasibility of problem-solving therapy for psychological distress experienced by Japanese early-stage breast cancer patients. Participants were 36 post-surgery Japanese breast cancer patients in a university hospital located in Osaka Prefecture, Japan. After screening for psychological distress using the Distress and Impact Thermometer and the Hospital Anxiety and Depression Scale, highly distressed patients were exposed to 5 weekly sessions of the problem-solving therapy program. Nineteen patients completed the intervention and follow-up. There was a significant difference between the pre-intervention and the 3-month follow-up in the total Hospital Anxiety and Depression Scale score (P = 0.02), and the mean change score from the pre-intervention to the follow-up was 6.05 (SD = 1.94). The intervention had a large effect size (d = 0.82). There were also significant changes in worry, self-efficacy and quality of life measures. The findings of our study suggest that the problem-solving therapy program has potential to be effective for alleviating psychological distress experienced by Japanese early-stage breast cancer patients. The true effectiveness of the program should be confirmed by a future randomized control trial.