ObjectiveFamily caregivers (FCs) of breast cancer patients play a vital role throughout the treatment process. Psychological distress of FCs is common and often ignored. A simple and effective instrument for screening psychological distress would help in selecting those FCs requiring special attention and intervention. Here, the validity of distress thermometer (DT) in FCs of Chinese breast cancer patients receiving postoperative chemotherapy was assessed, and the prevalence of anxiety and depression was evaluated.MethodsWe recruited 200 FCs of hospitalized breast cancer patients in this cross-sectional descriptive study. Before the first cycle of adjuvant chemotherapy, the levels of anxiety and depression among FCs were assessed using DT and Hospital Anxiety and Depression Scale (HADS). In total, 191 valid cases were analyzed. HADS was used as the diagnostic standard to assess the effectiveness of DT as a screening tool for anxiety and depression as well as to analyze the diagnostic efficiency of DT at various cutoff points.ResultsThe definitive prevalence of both anxiety and depression was 8.90%. The mean level of anxiety and depression among FCs was 5.64±3.69 and 5.09±3.85, respectively, both of which were significantly higher than corresponding Chinese norms (P<0.01). The areas under receiver operating characteristic curves of DT for the diagnoses of FCs’ anxiety and depression were 0.904 and 0.885, respectively. A cutoff value of 5 produced the best diagnostic effects of DT for anxiety and depression.ConclusionsThe levels of both anxiety and depression were higher in the FCs of Chinese breast cancer patients receiving postoperative chemotherapy than the national norm. DT might be an effective tool to initially screen psychological distress among FCs. This process could be integrated into the palliative care of breast cancer patients and warrant further research.