Personalized Radiation Oncology for Breast Cancer: The New Frontier
Menée sur 769 patientes atteintes d'un cancer du sein de stade précoce et incluses dans un essai évaluant le tamoxifène en combinaison ou non avec une radiothérapie (durée médiane de survie : 10 ans), cette étude évalue l'intérêt de déterminer, à l'aide de biomarqueurs immunohistochimiques, le sous-type de la tumeur pour prédire le risque de récidive ipsilatérale puis le bénéfice associé à une radiothérapie
Radiation therapy (RT) to the breast after breast-conserving surgery (BCS) is considered a standard of care for most women with early-stage invasive breast cancer.1 Adjuvant RT has repeatedly been shown to decrease the risk of an in-breast recurrence. Although no single study has shown a survival benefit to the addition of RT, a meta-analysis of randomized studies1 including 10,801 patients showed a 10-year reduction in any first recurrence from 35% to 19.3% with radiation (P < .001), which translated to a 3.8% absolute improvement in breast cancer–specific survival at 15 years (25.2% to 21.4%; P < .001). However, the survival benefit was not uniform across all risk groups. When stratified by absolute difference in 10-year risk of recurrence, patients who experienced an improvement greater than 20% with RT had a corresponding 7.8% difference in 15-year breast cancer mortality. However, for patients with an absolute improvement less than 10%, the breast cancer mortality benefit was only 0.1% (absolute mortality reduction trend P = .03). Moreover, RT is inconvenient, has some toxicity,2 and adds costs to the health care system.3 Identifying a group of patients with sufficiently low risk of recurrence, such that RT has no meaningful impact on survival and can therefore be reasonably omitted, has therefore been the goal of multiple randomized and single-arm studies.
Journal of Clinical Oncology , éditorial en libre accès, 2015