ESTRO 2025 Congress report I Physics track
Proffered paper session on Highlights predicting toxicities I Saturday, 3 May 2025
The evidence that cardiac calcifications (CACs) are associated with cardiac toxicity after post-operative radiotherapy of breast cancer started to emerge from several investigations on modern cohorts. However, the potential interplay between the cardiac dose, other non-dosimetry factors, and the presence/severity of CAC is almost unexplored. The work by Dimayuga B, Belardo A et al, presented at ESTRO and part of the EU-funded TETRIS project (HORIZON- EURATOM-2023-NRT-01 Grant Agreement number: 101166699), dealt with this topical issue. In summary, 29/1091 patients of a large cohort from a single centre experienced cardiac events (median follow-up: 6.5y). Quantitative CAC scores were found to be strongly associated with a higher risk of experiencing cardiac problems: the Agatston score (AS), well known in the field of cardio-oncology, and two “easy” scores (the volume of CAC and the maximum HU value in the heart), that showed similar performances compared to AS. Three-variable models, combining mean heart dose (MHD, encoded according to the optimal cut-off, MHD>1Gy), age, and CAC score, showed strong ability in predicting the risk of cardiac event, almost independently of the CAC score used (AS, volume, Max_HU). Figure 1 shows the risk of cardiac toxicity against Max_HU for patients with MHD above/below 1 Gy (once fixed the age to the median value of 62 years). Max_HU was found to be more reliable than CAC volume when comparing their values using an in-house script or our clinical TPS. Results show that CACs are the most important predictors of cardiotoxicity and that Max_HU is promising for fast assessment of patients at risk.
The importance of assessing the cardiac risk class of patients is high, as recently underlined by the ESC cardio-oncology guidelines. Although most patients treated nowadays stay in a quite safe area, due to the limited heart irradiation, the absolute number of breast cancer patients treated with RT worldwide makes the issue highly relevant. Very importantly, apart from the possibility to better refine planning and delivery approaches, the a priori assessment of patients at risk is also relevant to personalise follow-up programmes (hopefully with a strict collaboration between radiation oncologists and cardiologists), to prevent and identify the early signs of the occurrence of cardiac diseases.
Surely, this work improves our knowledge in the field. Its potential impact on daily practice is high, making available to the community a new paradigm to be considered in the therapy decision phase and in plan optimisation. A quite clear consequence is that the largest clinical benefit of further heart sparing should be expected in left breast cancer patients with moderate-severe CAC scores (Max_HU>250), and this could help physicians in selecting patients who deserve stressed heart-sparing techniques (such as deep breath hold).
Figure 1
Bjorn Kerby Dimayuga
Medical Physics, IRCCS San Raffaele Scientific Institute
Milan, Italy
Alfonso Belardo
Medical Physics, IRCCS San Raffaele Scientific Institute
Milan, Italy
References
Quantitative scores of cardiac calcifications detected on planning CT predict long-term cardiotoxicity after radiotherapy for breast cancer
Dimayuga K B1, Belardo A1, Perna L1, Fodor A2, Mangili P1, Del Vecchio A1, Di Muzio N G2,3, Fiorino C1
1 Medical Physics, IRCCS San Raffaele Scientific Institute, Milan, Italy
2 Radiation Oncology, IRCCS San Raffaele Scientific Institute, Milan, Italy
3 Faculty of Medicine and Surgery, Vita-Salute San Raffaele University, Milan, Italy
Presentation Number: E25-1864