The objective of this study is to determine whether there is a relationship between cancer patients' perceptions of the person-centeredness of their treatment experience and their anxiety levels during treatment.A questionnaire was distributed to adult cancer patients going through external beam radiotherapy (RT) with curative intent at a university hospital in Sweden (n = 892), which included two surveys, the State Trait Anxiety Inventory-state specific questions (STAI-S), and the Patient-centered Climate Questionnaire (PCQ) and additional treatment-specific questions. Eligible patients were provided with the questionnaire on their seventh day of RT by an RT-nurse.Statistical analysis showed a significant negative relationship between STAI-S scores and PCQ scores, and a significant positive relationship between the Treatment Environment questions and the STAI-S scores. Multivariate regression modeling found the PCQ subscale of safety to have the strongest negative association with STAI-S scores, showing that a climate of safety can significantly decrease patient situational anxiety levels. On the other hand, difficulty tolerating the overall treatment experience, worry about the treatment equipment, or feelings of isolation or claustrophobia within the treatment room all significantly factor into increases in patient-reported situational anxiety levels.Both the treatment environment and the psychosocial climate of the RT clinic significantly impact cancer patient state anxiety levels. These findings suggest that actively employing a person-centered approach during RT, and designing the treatment environment to be more attentive to the patient experience can both play a significant role in decreasing patient situational anxiety during treatment.