This study aimed to understand the actual state of psychological adjustment in cancer survivors undergoing radiotherapy and examine associated factors through evaluation of patient concerns. A questionnaire was administered to 200 outpatients who underwent radiotherapy. Psychological adjustment was measured using thePsychological Adjustment of Cancer Survivors (PACS) scale and analyzed using items on the Concerns Scale for Cancer Patients Receiving Radiotherapy and patient attributes. A multiple regression analysis was conducted using PACS as the dependent variable. Consequently, 121 responses were returned (response rate: 61.0%) . The results suggested that many cancer patients undergoing radiotherapy had achieved a certain level of psychological stability even in the early stages of treatment. Factors associated with psychological adjustment included age, employment status, performance status (PS), presence of a counselor, and concerns about living with cancer. Concerns about living with cancer were significantly associated with psychological adjustment, suggesting that such anxiety and conflict may hinder emotional stability and recovery.