Sophie Jacob

Two years after breast cancer radiotherapy, cardiac CT demonstrated dose-associated progression of coronary artery calcification, particularly in the presence of preexisting calcification, while coronary stenosis progression was unrelated to radiation dose.

The classification of harmful radiation-induced effects into ‘stochastic’ and ‘deterministic’ or ‘cancer/heritable effects’ and ‘tissue reactions’ has played a significant role in the recommendations of the International Commission on Radiological Protection (ICRP) over a number of decades. More recently, however, there has been a debate regarding the adequacy of the current scheme for classification of health effects with current scientific evidence. While these scientific aspects are discussed in greater detail in a parallel article, we will emphasise the practical importance of the classification itself here. The setting of dose limits is quite different for ‘deterministic’ and ‘stochastic’ effects. In the first case, provided reliable data regarding the threshold doses for radiation effects on a particular tissue are available, the dose limit is supposed to avoid harm altogether. With ‘stochastic effects’, the expected risks at the dose limit are supposed to be ‘tolerable’. Below the dose limit, optimisation must be aimed for based on the ‘prudent’ assumption that the stochastic risks linearly depend on the dose and that there is no threshold. If the distinction between the two kinds of harmful effects is drawn into question, possible consequences for the system of radiological protection need to be considered, especially in the context of its aims as they currently apply, namely, ‘to manage and control exposures to ionising radiation so that deterministic effects are prevented, and the risks of stochastic effects are reduced to the extent reasonably achievable’. It may be necessary, moreover, to discuss if and how the terminology used by ICRP (and others), in particular the terms ‘deterministic effects’ and ‘tissue reactions’, should continue to be used for the classification of radiation effects.

In the current system of radiological protection, radiation effects are classified as either tissue reactions (also known as deterministic effects) or stochastic effects. The objectives of the system are to manage and control exposures to ionising radiation so that harmful tissue reactions are prevented, and the risks of stochastic effects are reduced to the extent reasonably achievable. Thus, the classification of health effects is a very important pillar of the system of radiological protection. In recent years, there has been debate regarding the adequacy of the current scheme for classifying health effects. Recent publications, including those from ICRP, have highlighted the need for a review of the ICRP scheme for health effects classification. This article outlines the basis for the establishment of ICRP Task Group (TG) 123 and the outlined tasks, the key sources of uncertainties for consideration, the agreed approach and timeline to tackle the above tasks, as well as the links with and dependencies on the other ongoing developments to the system being considered by the other ICRP task groups.

Background and purpose Radiotherapy (RT) for breast cancer (BC) may induce subclinical myocardial injury. Longitudinal trajectories of N-terminal pro-B-type natriuretic peptide (NT-proBNP), a biomarker of myocardial stress, remain insufficiently characterized. We aimed to assess changes in NT-proBNP over 2 years after RT, identify clinical and treatment-related determinants, and evaluate associations with cancer therapy–related cardiac dysfunction (CTRCD). Methods NT-proBNP was measured before RT, at RT completion, and at 6 and 24 months among 101 BC patients treated with adjuvant RT without chemotherapy. Echocardiography was performed longitudinally, and CTRCD was defined according to 2022 ESC Cardio-Oncology guidelines. Determinants of NT-proBNP trajectories were analyzed using linear mixed-effects models. Logistic regression assessed associations between NT-proBNP and CTRCD. Results NT-proBNP remained stable at the end of RT and at 6 months but increased at 24 months (β = 0.147, p < 0.0001; +16%). Baseline NT-proBNP strongly impacted follow-up levels. Hypercholesterolemia (β = 0.252, p = 0.01), slightly moderate hypofractionated RT (20 × 2.35 Gy; β = 0.372, p = 0.0008), and aromatase inhibitor therapy (β = 0.258, p = 0.019) were independently associated with higher NT-proBNP at 24 months, whereas cardiac dose metrics were not. Seventeen patients developed CTRCD. NT-proBNP >400 ng/L at 24 months was associated with CTRCD (OR = 6.5, 95% CI 1.24-33.85; p = 0.027). Conclusion NT-proBNP increases 2 years after breast RT, influenced by baseline level, cardiometabolic, RT fractionation, and endocrine factors. Elevated NT-proBNP identifies patients at higher risk of subclinical cardiac dysfunction, supporting longitudinal biomarker monitoring in cardio-oncology surveillance.

The International Commission of Radiological Protection (ICRP) has made a review of the system of radiological protection toward a revision of general recommendations. The management of tissue reactions, previously known as deterministic effects, has always been a core aspect of the system of radiological protection. It is directly related to the health objectives of the system, which aims to prevent such effects. Tissue reactions, currently defined as ‘ injury in populations of cells characterised by a threshold dose and an increase in the severity of the reaction as the dose is increased further ’, are, in theory, prevented when dose remains below the threshold. This has significant implications for the system, including in relation to the setting of individual dose limits. This article reviews and discusses the approach proposed by the Commission with regards to the management of tissue reactions. It is based on the review of a set of relevant ICRP Publications, with the aim of contributing to the ongoing work on the review of the system of radiological protection.

Radiation-induced cardiotoxicity remains a significant concern in breast cancer (BC) patients treated with radiotherapy (RT), with both cardiac radiation exposure and systemic inflammation emerging as key contributors to early cardiovascular complications. This study investigated whether cardiac radiation dose triggers independently or synergistically with systemic inflammation, characterized by C-reactive protein (CRP) elevation to predict coronary artery calcification (CAC) progression in BC survivors. We analyzed 101 chemotherapy-naïve BC women who underwent cardiac CT before and 24 months after RT, with dosimetric analysis of left ventricle (LV) radiation exposure. Sustained CRP elevation was defined as increased CRP at both end of RT and 6 months post-RT. CAC progression was observed in 28 patients (27.7%). Both sustained CRP elevation (OR = 3.42; 95% CI: 1.12–10.5) and mean LV dose (OR = 1.20 per Gy; 95% CI: 1.03–1.40) were independently associated with CAC progression. Although no statistically significant interaction was observed, stratified analyses showed a stronger association between mean LV dose and CAC progression among patients with sustained inflammation (OR = 1.39, 95%CI: 1.07–1.81), whereas this association was weaker and non-significant in patients without systemic inflammation (OR = 1.12, non-significant). The combined model incorporating both predictors showed improved discriminative performance (AUC = 0.733). These findings suggest that systemic inflammation may amplify the effect of cardiac irradiation and that combining inflammatory and dosimetric data improves early prediction of CAC risk. This may help identify high-risk subgroups who could benefit from enhanced cardiovascular monitoring or preventive strategies after BC RT.

Background: Catheter ablation is a key treatment for atrial fibrillation (AF). This procedure is clearly identifiable in French medical‐administrative databases and can be used as a surrogate for symptomatic patients with drug‐refractory or symptomatic paroxysmal AF forms. Breast cancer (BC) patients have an increased risk of AF, but knowledge about AF forms treated by ablation is limited.Aims: Based on a representative cohort of BC patients from the French National Health Databases, we aimed to assess the occurrence of AF catheter ablation in these patients, compared to the general population.Methods: Patients with a first diagnosis of BC between 2008 and 2018 and followed for at least 1 year until 2019 were eligible. The incidence rates of AF ablation among BC patients were compared to those in the general population by estimating a standardized incidence ratio (SIR). A competing risk survival model was used to evaluate the occurrence of AF ablation in BC patients treated with or without radiotherapy (RT) (subdistribution Hazard Ratio—sdHR).Results: We included 3667 patients (78% with RT). Overall, 16 cases underwent AF ablation, whereas 8.3 cases were expected in the general population, resulting in a significant SIR of 1.93 [1.10–3.00] (p < 0.05). After a mean follow‐up of 6.6 years, the cumulative incidence of AF ablation at 5 years was 0.14% [0.05–0.35] in the RT group and 0.47% [0.13–1.31] in the non‐RT group, with no significant difference in the age‐adjusted survival analysis (sdHR = 0.65 [0.21–2.01]).Conclusions: Our exploratory study revealed that BC patients had a twofold greater rate of first AF ablation than the age‐comparable general population, without a link with RT. These results should be interpreted cautiously because of the limited size of the study population and the differing characteristics between the RT and non‐RT groups.

Background: Atrial fibrillation (AF) after radiotherapy (RT) in patients with breast cancer (BC) is a relatively new and understudied topic. AF can increase the risk of stroke and other serious cardiovascular complications, compromising patients’ quality of life and survival. Screening of AF, both asymptomatic and symptomatic forms, is therefore essential for optimal management. Objective: The aim of the Watch Your Heart After Radiotherapy for Breast Cancer (WATCH) study is to assess the incidence of AF (symptomatic or asymptomatic) occurring throughout a 5-year follow-up after RT and to investigate whether cardiac radiation exposure is associated with the occurrence of such events. Methods: WATCH is a cohort study that will include 200 patients over 65 years old, treated with RT for BC 5 years before inclusion and without a history of AF. Cross-sectional screening for AF at the time of the scheduled 5-year post-RT visit will be conducted by recording data from a Withings ScanWatch smartwatch for 1 month, confirmed by an electrocardiogram (ECG), and validated by a physician. In addition, a transthoracic echocardiography (TTE) will be performed, providing a comprehensive assessment of cardiac structures, and allowing us to investigate the underlying etiology and assess the risk of complications. Patients’ medical records will provide retrospective information about the timing and risk factors for the occurrence of AF and other arrhythmias and cardiac diseases during the 5 years following RT. The development of deep learning algorithms for autosegmentation analysis of potentially critical substructures for the occurrence of AF, including cardiac chambers, the sinoatrial node, the atrioventricular node, coronary arteries, and pulmonary veins (PVs), will produce dosimetry linked to previous RT treatment for all contoured structures. Results: Enrollment started in October 2023 and will continue until mid-2026 to include 200 patients, which will ensure an 80% statistical power to detect a significant difference in AF incidence around 15% for the group of patients moderately exposed (75th percentile of the mean heart radiation dose). The results are expected by the end of 2026. Conclusions: This study will contribute to generating new knowledge on AF after RT for BC and help considering the inclusion of AF screening into routine clinical practice for these patients. Identifying the dose-risk associations would improve RT delivery protocols to limit the occurrence of different forms of AF and, if necessary, initiate appropriate treatment. Trial Registration: ClinicalTrials.gov NCT06073509; clinicaltrials.gov/study/NCT06073509?id=NCT06073509&rank=1. International Registered Report Identifier (IRRID): DERR1-10.2196/67875