OBJECTIVES: EFA may be useful for assessing the efficiency of newer interventions.  This study evaluated whether EFA could be useful in identifying the efficiency of mBC therapies adopted by the NHS, and to identify the efficiency frontier for newer technologies. METHODS: A literature search identified mBC treatments that underwent HTA in the UK.  Reports were reviewed to identify treatment efficacy and HTA recommendations.  Costs were determined for a course of treatment.  The incremental costs per patient were plotted on the horizontal axis and incremental median overall survival (ΔOS) of treatment was plotted on the vertical axis to construct the EFA line.  Treatments below this line are considered inefficient.  Treatments above this line have better OS and may redefine the efficiency frontier.  Treatments in the upper right quadrant beyond the frontier line are in an area where ceiling price has not been defined.  Treatments in the lower right quadrant beyond the frontier line are inefficient due to higher cost for lower OS. RESULTS: Ten reports that evaluated efficacy in terms of median OS were included in the EFA.  The therapies are paclitaxel albumin, gemcitabine, trastuzumab, bevacizumab, lapatinib, eribulin and fulvestrant.  On the frontier line are paclitaxel albumin (ΔOS of 2.3 months at £2020), gemcitabine (ΔOS of 2.8 months at £6020), and trastuzumab (ΔOS of 4 months at £16939); all received positive recommendations.  Lapatinib (ΔOS of 1.9 months at £10180), bevacizumab (ΔOS of 1.7 months at £36560), eribulin (ΔOS of 2.5 months at £4834) and fulvestrant (ΔOS of 2.3 months at £2481) are all below the frontier line and received negative recommendations. CONCLUSIONS: EFA may be a useful method for assessing the efficiency of new mBC treatment options for clinical use.  Further studies are needed to better understand value in terms of efficiency of treatments in other tumor types and disease areas.