PURPOSE: Unresectable chest wall recurrences of breast cancer (CWR) in heavily pretreated patients are especially difficult to treat. We hypothesised that thermally enhanced drug delivery using low temperature liposomal doxorubicin (LTLD), given with mild local hyperthermia (MLHT), will be safe and effective in this population. PATIENTS AND METHODS: This paper combines the results of two similarly designed phase I trials. Eligible CWR patients had progressed on the chest wall after prior hormone therapy, chemotherapy, and radiotherapy. Patients were to get six cycles of LTLD every 21-35 days, followed immediately by chest wall MLHT for 1 hour at 40-42 °C. In the first trial 18 subjects received LTLD at 20, 30, or 40 mg/m2; in the second trial, 11 subjects received LTLD at 40 or 50 mg/m2. RESULTS: The median age of all 29 patients enrolled was 57 years. Thirteen patients (45%) had distant metastases on enrolment. Patients had received a median dose of 256 mg/m2 of prior anthracyclines and a median dose of 61 Gy of prior radiation. The median number of study treatments that subjects completed was four. The maximum tolerated dose was 50 mg/m2, with seven subjects (24%) developing reversible grade 3-4 neutropenia and four (14%) reversible grade 3-4 leucopenia. The rate of overall local response was 48% (14/29, 95% CI: 30-66%), with. five patients (17%) achieving complete local responses and nine patients (31%) having partial local responses. CONCLUSION: LTLD at 50 mg/m2 and MLHT is safe. This combined therapy produces objective responses in heavily pretreated CWR patients. Future work should test thermally enhanced LTLD delivery in a less advanced patient population.