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Simple Summary: A cohort of 123 women with stage I-II breast cancer enrolled in a prospective clinical trial of adjuvant radiotherapy who were followed for over 10 years. Year 2020 was associated with excess mortality. The number of deaths (n = 5) in that single year represented a third of all deaths (n = 15) in the full decade before. There was in that year a significant increase in lung-heart toxicity and a significant decline in lung-heart function as measured by left ventricular ejection fraction, forced vital capacity and carbon-monoxide diffusing capacity. We investigated lung-heart toxicity and mortality in 123 women with stage I-II breast cancer enrolled in 2007–2011 in a prospective trial of adjuvant radiotherapy (TomoBreast). We were concerned whether the COVID-19 pandemic affected the outcomes. All patients were analyzed as a single cohort. Lung-heart status was reverse-scored as freedom from adverse-events (fAE) on a 1–5 scale. Left ventricular ejection fraction (LVEF) and pulmonary function tests were untransformed. Statistical analyses applied least-square regression to calendar-year aggregated data. The significance of outliers was determined using the Dixon and the Grubbs corrected tests. At 12.0 years median follow-up, 103 patients remained alive; 10-years overall survival was 87.8%. In 2007–2019, 15 patients died, of whom 11 were cancer-related deaths. In 2020, five patients died, none of whom from cancer. fAE and lung-heart function declined gradually over a decade through 2019, but deteriorated markedly in 2020: fAE dipped significantly from 4.6–4.6 to 4.3–4.2; LVEF dipped to 58.4% versus the expected 60.3% (PDixon = 0.021, PGrubbs = 0.054); forced vital capacity dipped to 2.4 L vs. 2.6 L (PDixon = 0.043, PGrubbs = 0.181); carbon-monoxide diffusing capacity dipped to 12.6 mL/min/mmHg vs. 15.2 (PDixon = 0.008, PGrubbs = 0.006). In conclusion, excess non-cancer mortality was observed in 2020. Deaths in that year totaled one-third of the deaths in the previous decade, and revealed observable lung-heart deterioration. [ABSTRACT FROM AUTHOR]

Purpose: Previous studies in patients with breast cancer have shown acute radiation therapy-induced reductions of pulmonary diffusing capacity, essentially owing to lung volume restriction. We aimed to assess the long-term effect of 2 radiation therapy regimens, which differed in terms of radiation technique and dose fractionation, on lung function.Methods and Materials: From a randomized controlled trial comparing conventional 3-dimensional conformal radiation therapy (CR) and hypofractionated tomotherapy (TT), 84 patients with breast cancer (age at inclusion 54 ± 10 [standard deviation] years) could be assessed at baseline, after 3 months, and after 1, 2, 3, and 10 years. Measurements included forced vital capacity, total lung capacity (TLC), and diffusing capacity (TLco).Results: Radiation therapy-induced lung function changes over 10 years (Δ) were similar for both treatment arms, and in a patient subgroup with negligible history of respiratory disease or smoking (n = 57) these averaged: Δ forced vital capacity = -13 (± 9) percent predicted; ΔTLco = -14 (± 12) percent predicted; and ΔTLC = -11 (± 9) percent predicted. The only significant correlation was between V20 (lung volume exposed to dose exceeding 20 Gy) and ΔTLco (rho = -0.36; P = .007). In this subgroup, as well as in the entire patient cohort, the incurred pulmonary restriction in terms of TLC and TLco showed a greater decline at 3 months for CR versus TT. However, at 10 years, no significant difference could be detected between CR and TT (P = .9 for TLC and P = .2 for TLco in the entire patient cohort). Of the patients with normal TLC and TLco at baseline (ie, above lower limits of normal), respectively 94% and 96% were still normal 10 years later.Conclusions: In women with breast cancer, conventional 3-dimensional conformal radiation therapy and hypofractionated tomotherapy induce similar restrictive lung patterns during the course of a 10-year period, despite some treatment-dependent differences in the first 3 months. The large majority of women with normal lung function at baseline maintained a normal lung function status 10 years after radiation therapy, irrespective of treatment arm. [ABSTRACT FROM AUTHOR]