Effects of Smoking on Late Toxicity From Breast Radiation
A partir d'une revue systématique de la littérature publiée entre 2010 et 2015 et à partir de données de 75 essais randomisés incluant 40 781 patientes atteintes d'un cancer du sein traité par radiothérapie, cette étude évalue l'association entre les doses de rayonnements reçues, le risque de décès par maladie cardiaque et le risque à long terme de développer un second cancer primitif, notamment un cancer du poumon, en fonction du statut tabagique des patientes
A defining success in the treatment of breast cancer has been the declining risk of local-regional recurrence as noted over the past three decades. For example, data compiled for the recent Consensus Guideline on Margins indicated that the absolute risk of in-breast tumor recurrence (IBTR) decreased by approximately 4% to 5% per decade of diagnosis from 1980 to 2005.1 This success is attributable to improvements in diagnostic imaging, surgical resection, pathologic assessment, systemic therapy, and radiation treatment planning.
An underappreciated corollary to this success is that, as baseline IBTR risk decreases, the absolute local control benefit derived from radiation similarly decreases. For example, in the classic National Surgical Adjuvant Breast and Bowel Project B-06 clinical trial, 20-year IBTR risk was 39% among women treated with lumpectomy alone compared with 14% among women treated with lumpectomy and radiation, a 25% absolute risk reduction.2 In contrast, the more contemporary National Cancer Institute of Canada randomized trial reported a 10-year IBTR risk of 14% with tamoxifen alone compared with 5% for tamoxifen plus radiation, a 9% absolute risk reduction.3
As the absolute benefit derived from radiation diminishes, small risks of serious adverse effects or deaths from radiation become more relevant to the calculus of determining who should or should not receive radiation. Within this context, the nuanced findings from Taylor et al4 in the article accompanying this editorial provide valuable and clear information with which to guide decision making. Specifically, Taylor et al4 should be commended for moving beyond their initial finding, summarized in the Data Supplement, that women who received radiation experienced a 3.1% absolute excess risk of nonbreast cancer mortality. If this estimated excess risk of death were applicable to current patients with early-stage breast cancer, then the appropriateness of radiation should be questioned.
However, Taylor et al4 demonstrate that the risks of late radiation morbidity and mortality for patients treated with modern radiotherapy techniques are considerably lower than might be assumed on the basis of their unadjusted, aggregated data. This lower risk is specifically attributable to three modifiable factors: (1) patient smoking status, (2) normal tissue doses, and (3) radiated target volume.(....)
Journal of Clinical Oncology , éditorial en libre accès, 2016