Partial breast irradiation: The time is there!

The conventionally fractionated partial breast irradiation (PBI) IMPORT LOW trial represents the perfect example of how an adequate selection of patients led to a minimal local relapse rate for patients. Coles and colleagues, demonstrated a 5-year non-inferiority local relapse rate for PBI compared to standard whole breast irradiation, together with a significant reduction in terms of breast toxicity using a conventional radiation technique implementable worldwide. Most of enrolled patients had early stage node negative, grade1-2, oestrogen receptor positive, human epidermal growth factor receptor 2 negative tumours. An exponential decrease in term of local relapse rate was observed from the first published PBI studies. The new high-level evidence provided by these results clearly demonstrates that while toxicity and cosmetic outcome concerns are strongly dependent on the technique, the efficacy of PBI is closely related to the adequate choice of patients. Upcoming data from several studies and from matured follow up of the published ones will be critical to confirm if also accelerated PBI could be accepted as a standard alternative to whole breast irradiation. However, we feel that IMPORT LOW inclusion criteria, together with tumour biology should be definitively integrated in the decision-making process.