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Proton radiotherapy (PRT) is associated with fewer late effects compared to photon radiotherapy (PHT) in selected survivors of childhood cancers. While PRT is more costly upfront, the reduction in long-term morbidity is expected to provide cost recovery to healthcare systems. We use real-world data (RWD) to compare physician claims and discharge abstract database (DAD) data in a cohort of pediatric patients receiving PRT or PHT. Using the Alberta Health Services (AHS) pediatric database, we identified those receiving radiotherapy (RT) between 2010 and 2022, inclusive, who met AHS guidelines for PRT referral to the United States. Patient demographics including follow-up time from RT start dates were determined. Data from the Alberta Pediatric Cancer Survivors cohort was abstracted including physician claims and DAD data after completion of RT. Canadian Institute for Health Information (CIHI) data was accessed to determine hospitalization costs per day for the year of admission. Univariate analysis was performed using the t-test at a significance level of 0.05. Records for 228 children were identified: 35 patients (15.4%) received PRT and 193 patients received PHT (84.7%). Median follow-up (FU) from RT was not different in children treated with PRT (6.34 years, IQR 5.16 years) and PHT (6.45 years, IQR 7.28 years, p = 0.509). The mean number of outpatient visits was lower following PRT (114.0, SD 94.5) vs PHT (179.0, SD 201.5, p = 0.005). Regarding inpatient hospitalizations, the mean length of stay (LOS) was lower after PRT (30.7 days, SD 30.2) vs PHT (52 days, SD 56.9, p = 0.017). We compared the cost of hospitalization 60 days post RT for the PRT and PHT groups. As patients receiving PRT received care of country, we 60 days post RT represented a time both groups would be eligible to receive care at home. The mean cost of hospitalization for the PRT group 60 days post RT was $5337.57 (SD = $7919.88). Comparatively the mean cost of hospitalization 60 days post RT for the photon group was $7053.25 (SD = $15.751.83). The trend towards higher cost of hospitalization seen for the PHT was not statistically significant (p = 0.07). PRT is associated with reduced outpatient physician visits and LOS after completion of RT compared to PHT using RWD. With reductions in LOS, there is potential cost savings with a lower mean cost of hospitalization 60 days post RT seen in the PRT group. While this trend did not reach statistical significance, small numbers of patients were represented in the PRT group. Assessment of claims cost and hospitalization costs over the entire follow-up period for this cohort of patients is planned. [ABSTRACT FROM AUTHOR]

Women with left sided breast cancer (BC) who receive adjuvant radiotherapy (RT) have increased risk of subsequent cardiac events, which may be mitigated by maintaining mean heart dose (MHD) below a threshold of 3 Gy. We hypothesized that early MRI evaluation of cardiac functional changes can identify acute cardiac insult and predict for the risk of long-term cardiac complications. Here we report the findings of a phase II prospective clinical trial evaluating RT-related LV structure and function using cardiac MRI in women with left sided BC treated with adjuvant RT. Patients with left sided BC were enrolled into a single institutional phase II study. After informed consent, patients were allocated for breast RT with free breathing (FB) or with deep inspiratory breath hold (DIBH) delivery, if the predicted MHD was ≤3 Gy (≤ 5 Gy, if also regional nodal RT) or > 3 Gy (> 5 Gy, if regional nodal RT), respectively, on initial FB planning. Cardiac MRI was performed at baseline (pre-RT), and at 16 and 52 weeks. Cardiac toxicity was defined as change in the indexed LV end diastolic volume (LVEDVi), LV ejection fraction (LVEF), indexed LV end systolic volume (LVESVi) and indexed LV mass (LV MASSi). Estimation of multiple serum cardiac biomarkers were also done at the three time points. Continuous variables were expressed as mean ± standard deviation, and ANOVA analysis was used to identify correlation between changes in cardiac parameters from baseline to 16 and 52 weeks, when compared to cardiac radiation dosimetric data. Of the 69 participants, 25 received RT with FB technique. 44 received RT with DIBH, of which 23 also had received adjuvant chemotherapy (CT) prior to RT. For the FB, DIBH (no CT), and DIBH (with CT) cohorts, MHD was 1.70 ± 0.93 Gy, 1.93 ± 1.30 Gy, and 2.26 ± 1.15 Gy and mean LV dose was 2.47 ± 1.48 Gy, 3.18 ± 1.93 Gy, and 3.23 ± 1.82 Gy, respectively. Evaluation of LVEDVi, LVEF, LVESVi, and LV MASSi showed no statistical difference between the 3 treatment arms. No statistical correlation was noted between LVEF changes (≥ 5% and ≥ 10% from baseline) and the cardiac dosimetric data; all p values > 0.1. Prior CT did not measurably impact cardiac function. In this prospective study, no significant post-RT cardiac events were demonstrable by functional imaging. This supports the significance of maintaining MHD ≤ 3 Gy to minimize or prevent RT related cardiac toxicity in women with left sided BC. Our observation warrants further investigation in a large prospective setting to evaluate late cardiac events. Analysis of serum cardiac biomarkers is currently ongoing. [ABSTRACT FROM AUTHOR]