The distress thermometer (DT), a one-item measure for distress, provides a means for rapidly and effectively screening psychological distress in cancer patients. In this pilot study, a screening efficacy of the DT was investigated in a mixed cohort of 108 Korean cancer patients. Participants completed the DT, the problem list (PL), and the Hospital Anxiety and Depression Scale (HADS), and answered questions regarding supportive needs and their degree of satisfaction with several aspects of care. Receiver operating characteristic (ROC) curve analyses indicated that a DT cutoff score of 4 yielded an area under the ROC curve of 0.75 with a sensitivity of 0.83 and a specificity of 0.59 for HADS-total score defined cases (> or =15). HADS--Anxiety and Depression subscale scores explained 27% of the variability in the DT scores, implying that 'distress' is a broader concept that includes anxiety and depressive symptoms but has a more comprehensive meaning that encompasses multiple contributory factors. Regarding the PL, distressed patients (DT> or =4) reported significantly more problems (23 of 35) in all categories, suggesting, although degrees differ, that a wide variety of problems contribute to distress in cancer patients. Distress as defined by DT and HADS subscale scores was also significantly associated with higher supportive needs, a poor ECOG performance status (both physician and patient-rated), and a reduced level of satisfaction with treatment, staff, and communications. In conclusion, the DT and the PL were found to be simple yet effective screening instruments for detecting psychosocial distress in Korean cancer patients, and for identifying problems that warrant intervention.