BackgroundIntra-individual heterogeneity of cardiac exposure is an issue in breast cancer (BC) radiotherapy that was poorly considered in previous cardiotoxicity studies mainly based on mean heart dose (MHD). This dosimetric study analyzes the distribution of individually-determined radiation doses to the heart and its substructures including coronary arteries and evaluate whether MHD is a relevant surrogate parameter of dose for these substructures.MethodsData were collected from the BACCARAT prospective study that included left or right unilateral BC patients treated with 3D-Conformal Radiotherapy (RT) between 2015 and 2017 and followed-up for 2 years with repeated cardiac imaging examinations. A coronary computed tomography angiography (CCTA) was performed before RT for all patients. Registration of the planning CT and CCTA images allowed delineation of the coronary arteries on the planning CT images. Using the 3D dose matrix generated during treatment planning and the added coronary contours, dose distributions were generated for whole heart and the following substructures: left ventricle (LV), left main coronary artery (LMCA), left anterior descending artery (LAD), left circumflex artery (LCX) and right coronary artery (RCA). A descriptive analysis of the physical doses in Gray (Gy) was performed, Dmean was the volume-weighted mean dose.ResultsDose distributions were generated for 89 left-sided BC patients (MHD = 2.9 ± 1.5 Gy, Dmean_LAD = 15.7 ± 3.1 Gy) and 15 right-sided BC patients (MHD = 0.5 ± 0.1 Gy; Dmean_RCA = 1.2 ± 0.4 Gy). For left-sided BC patients, the ratio Dmean_LAD/MHD was around 5. Pearson correlation coefficients between MHD and Dmean for delineated substructures were all statistically significant. However, for all substructures, the coefficient of determination R2 indicated that the proportion of the variance in Dmean of the substructure predictable from MHD was moderate to low (in particular R2 = 0.45 for LAD). Among left-sided BC patients with MHD < 3Gy, 56% of patients could nevertheless receive LAD doses above 40Gy (V40 > 0).ConclusionOur study illustrates that MHD is not enough to predict with confidence individual patient dose to the LV and coronary arteries, in particular the LAD. For precise radiotherapy-induced cardiotoxicity studies it would be necessary to consider the distribution of doses within these cardiac substructures rather than just the MHD.Trial registrationClinicalTrials.gov: NCT02605512, Registered 6 November 2015 - Retrospectively registered.

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Background In a previous phase II study an immunonutrient supplement was found to reduce severe acute toxicities for head and neck squamous cell cancer (HNSCC) patients treated with concomitant cisplatin and radiotherapy. Objectives The primary objective of the present study was to evaluate efficacy of the same immunonutrient supplement on severe mucositis. Secondary objectives included tolerance, compliance to oral supplementation, chemotherapy interruptions and delays, quality of life, and progression-free survival (PFS) and overall survival (OS) at 1, 2, and 3 y. Methods Between November 2009 and June 2013, 180 HNSCC patients eligible for adjuvant chemotherapy after surgery with curative intent were included in our double-blind phase III multicenter trial. They were assigned to receive oral supplementation (3 sachets/d) of either a formula enriched with l-arginine and omega-3 (n–3) fatty and ribonucleic acids (experimental arm), or an isocaloric isonitrogenous control (control arm), for 5 d before each of 3 cycles of cisplatin. Intention-to-treat (ITT) and per-protocol (PP) analyses were undertaken, along with subgroup analyses of ≥75% compliant patients, to compare the incidence of acute mucositis (Radiation Therapy Oncology Group and WHO scales) and 36-mo survival. Results At 1 mo after terminating chemoradiotherapy (CRT), no differences were observed in the incidence of grade 3–4 mucositis between treatment groups, in the ITT, PP (172 patients), and subgroup (≥75% compliance, n = 112) analyses. The immunomodulating supplement did not significantly improve survival in the ITT and PP analyses at 3 y after CRT. Among ≥75% compliant patients, however, OS at 3 y was significantly improved in the immunomodulating formula group (81%; 95% CI: 67%, 89%) compared with controls (61%; 95% CI: 46%, 73%; P = 0.034), as well as PFS (73%; 95% CI: 58%, 83% compared with 50%; 95% CI: 36%, 63%; P = 0.012). Conclusions Although this immunomodulating formula failed to reduce severe mucositis during CRT, the findings suggest that the long-term survival of compliant HNSCC patients was improved. This trial was registered at clinicaltrials.gov as NCT01149642.

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