How does one interpret the LUMINA trial in the FLORENCE APBI ERA?  

While I am encouraged by the results of the LUMINA trial with respect to identifying patients who are less likely to benefit from radiation therapy when committing to endocrine therapy, did it ask the right question?

"Adjuvant breast RT is usually prescribed following BCS to reduce the risk of local recurrence (LR). However, this treatment is inconvenient, costly, and associated with acute and late toxicity."

These patients are generally excellent candidates for 5 fraction partial breast radiation using the Florence IMRT regimen. The regimen is more convenient and cost effective than moderately hypofractionated whole breast radiation, and the toxicity profile is very favorable. Unlike endocrine therapy, essentially all patients who will initiate 5 fraction partial breast radiation therapy will complete the therapy.

Is it time to cede T1N0 luminal A patients to endocrine therapy, or simply to shift to one modality rather than multimodal adjuvant approaches?