Background: CT-induced DCR of MBC is reported only anecdotally. The addition of HER2-Tx to conventional CT results in increased response rates and prolonged survival for pts with HER2+ MBC. We previously reported that a minority of pts with HER2+ MBC can achieve prolonged CR but their long-term outcome remains unclear. Methods: We conducted a systematic retrospective review of all pts with HER2+ MBC treated at our Institution with any CT+HER2-Tx and identified DCR. DCR was defined as a complete response according to RECIST 1.1 criteria lasting >36 months. Results: Between January 2000 and December 2010 168 consecutive pts with HER2+ MBC were commenced on CT+HER2-Tx. We identified 17 pts (10%) who met criteria for DCR. Their characteristics are: median age: 53yrs (range 30-65), oestrogen receptors (ER): neg 53%/pos 47%, sites of distant metastases: visceral 47%/lymph nodes only 35%/bone and soft tissues 12%, unknown 6%. All pts received trastuzumab (T). Chemotherapy regimens were: docetaxel+carboplatin 64%/docetaxel+lapatinib 18%/single agent taxane 6%/capecitabine 6%/unknown 6%. Metastatic disease was biopsy-proven in 9/17 pts (53%). All pts received maintenance HER2-Tx after completion of CT. Median FU is 6.5 yrs (range 3.4-13.6). Median duration of HER2-Tx is 61 months (41-127+). Two pts (12%) had MBC relapse while on maintenance T, 1 pt had a second HER2+ primary BC and underwent curative surgery. At database cut-off date (1/2/2014) 15 pts (88%) are alive and disease-free. Their characteristics are: all 1st-line therapy, ER neg 53%, single site of distant metastases 73% (lymph nodes 40%, liver 33%). Conclusions: To our knowledge this is the largest series analyzing long-term outcome of HER2+ MBC pts with DCR after CT+HER2-Tx. Our mature results show that a subgroup of pts can achieve a very prolonged CR thus prompting speculations that they have been cured from HER2+ MBC. These pts are usually treated in the 1st-line setting, have more frequently ER-negative disease and limited metastatic disease. Prolonged HER2-Tx could play a role in maintaining DCR. We are currently investigating the molecular profile of this subset of pts.