Cancer treatment including radiotherapy reduces residual inflammatory risk in women with breast cancer

Abstract

International audienceBackground Radiotherapy is believed to induce vascular injury in patients with cancer. However, the link between radiation therapy and cardiovascular risk remains unclear, particularly in women with breast cancer where the coronary arteries are directly radiated. Purpose To explore the direct impact of cancer treatment including radiotherapy (RT) on coronary inflammation and the residual inflammatory risk in women with breast cancer. Methods This prospective study included 101 breast cancer patients from the BACCARAT study treated with RT without chemotherapy. CCTA images were taken at baseline (before RT) and two years following RT. Coronary inflammation was measured in each coronary artery using the perivascular Fat Attenuation Index (FAI) Score, an established quantitative metric of coronary inflammation, corrected for age and gender. The residual inflammatory risk was quantified using the CaRi-Heart prognostic model that integrates FAI Score with clinical risk factors (diabetes, smoking, hyperlipidaemia, and hypertension) and coronary plaque burden, as previously described. Results Two years after RT, 83 patients had a complete set of paired analysable CCTAs. There was a marked parallel reduction of vascular inflammation at follow-up, as captured by the significant reduction in FAI score percentiles across all epicardial coronaries (p<0.0001 for RCA, p=0.031 for LAD, p=0.009 for LCX, a-c). Despite the increase in coronary calcification (p<0.001, d), the predicted 8-year risk for fatal cardiac events (CaRi-Heart Risk) was reduced by 14% in this population two years after radiotherapy (p=0.014, e). No change was observed in total epicardial adipose tissue (EpAT) volume (p=0.17), while there was no significant association between coronary inflammation and the amount of radiation exposure of the heart (f). Importantly, there was a meaningful risk reclassification 2 years after radiotherapy, with 45.9% of the high-risk patients reclassified to lower risk categories, and a parallel expansion of the "low" risk population from 8.5% to 24.4% (g). Conclusion This study demonstrates that cancer treatment including radiotherapy decreases baseline coronary inflammation and leads to significant reduction of the residual inflammatory risk in women with breast cancer, two years after treatment (h). The parallel increase of coronary calcification suggests plaque stabilization as coronary inflammation is reduced, and supports that vascular inflammation triggered by the tumour itself, rather than the radiotherapy, may partly explain increased cardiovascular risk in these women