Omission of radiation therapy after breast-conserving surgery for biologically favourable tumours in younger patients: the wrong answer to the right question

In this perspective paper, the findings of the recently published LUMINA study are critically evaluated, with an emphasis on the need for cautious interpretation and a nuanced approach in clinical practice. The LUMINA trial, which investigates the role of adjuvant endocrine therapy in low-risk breast cancer patients, is assessed for its limitations, including a highly selective patient cohort and an insufficient follow-up period. Questions are raised about the arbitrary nature of certain trial criteria, such as the Ki67 cut-off and oestrogen receptor positivity threshold, and their suitability for defining treatment protocols. Concerns are also expressed regarding the reported high compliance with endocrine therapy and its underestimation of side effects, with attention drawn to the significant impact on patients' quality of life. The importance of long-term data and further trials to inform clinical decisions effectively is emphasized. While the LUMINA study does not support a change in practice, it is seen as a foundation for generating hypotheses to guide ongoing clinical trials. The need for a patient-cantered approach is stressed, considering individual wishes and desires in decision-making, despite the complexity of articulating these aspects in guidelines. In conclusion, it is reiterated that the omission of radiation therapy remains an investigational avenue at this stage, and a nuanced interpretation of available findings is essential to ensure sound clinical decision-making.