Reduced mortality with partial breast irradiation for early breast cancer – a meta-analysis of randomised trials
A partir d'une revue de la littérature publiée jusqu'en novembre 2015 (9 essais), cette méta-analyse met en évidence, par rapport à une radiothérapie du sein entier et du point de vue de la mortalité à 5 ans, l'intérêt d'une irradiation mammaire partielle chez les patientes atteintes d'un cancer du sein de stade précoce (8 720 cas)
Background : With earlier detection and more effective treatment, mortality from breast cancer continues to fall and it has become increasingly important to reduce the toxicity of treatments. Partial breast radiotherapy, which focuses radiation to the tumour bed may achieve this aim. We analysed mortality differences in randomised trials of partial breast irradiation. Method : We included data from published randomized trials of partial breast irradiation (alone or as part of a risk-adapted approach) vs. whole breast irradiation for invasive breast cancer suitable for breast conservation therapy We identified trials using Pubmed and Google search with the terms “partial breast irradiation” OR “intraoperative radiotherapy” OR “IMRT” OR (“accelerated” AND “radiation”) AND “randomised / randomized”, and as well as through discussion with colleagues in the field. We calculated the proportion of patients who had events in each randomised arm at 5 years follow up and created a Forest plot using STATA version 14.1. Results : We identified 9 randomised trials of PBI vs. WBI in invasive breast cancer; 5-year outcomes were available for non-breast-cancer mortality in 5 trials (n=4489) and for breast-cancer mortality in 4 trials (n=4231). The overall mortality was 4.9%. There was no detectable heterogeneity between the trials for any of the outcomes. There was no difference in proportion of patients dying from breast cancer (difference 0.000% (95% CI -0.7 to +0.7), p=0.999). Non-breast cancer mortality with PBI was lower than WBI (difference 1.1% (95% CI -2.1% to -0.2%), p=0.023). Total mortality with PBI was also lower than WBI (difference 1.3% (95%CI -2.5% – 0.0%), p=0.05). Implications : Use of PBI instead of WBI in selected patients results in a lower 5-year non-breast-cancer and overall mortality, amounting to a 25% reduction in relative terms. This information should be included when breast conserving therapy is proposed to a patient.