The use of interventions for cancer-related distress is important to reduce this distress. Distress has a negative impact on quality of life, the recovery during and after treatment and may even adversely affect survival. There is insufficient attention to the systematic approach to psychosocial problems in cancer patients in the Netherlands. A task force discussed and studied which instrument measures psychosocial problems best. The distress thermometer ("lastmeter") had the best results. A guideline is written to use the distress thermometer for patients with cancer and will be used in hospitals in the Netherlands. However, it is not clear what the effects are of the use of the distress thermometer on the psychosocial wellbeing of the patient. Furthermore, it is also unknown whether the use of the distress thermometer leads to cost-effective care. The study focuses on the use of the distress thermometer in breast cancer patients. An efficiency study (RCT) will be conducted to evaluate the systematic use of the distress thermometer and its discussion by a nurse as compared to the usual care provided to outpatients who are treated with curative intent for breast cancer by their treating physicians. The clinical and economic impact of the use of the Distress thermometer will be assessed in comparison with usual care.The recruitment of patients will take place in the out-patient clinic of a university hospital. Patients will be followed from diagnose until two years after finishing their treatment.