Pneumonitis and fibrosis after breast cancer radiotherapy: occurrence and treatment-related predictors

Radiation pneumonitis (RP) and radiation fibrosis (RF) are common side effects after breast cancer (BC) radiotherapy (RT). However, there is a great variation in the frequency of RP and RF. This study presents the occurrence of- and the treatment-related predictors for RP and RF. Further, physician- and patient-reported pulmonary symptoms during the first year after postoperative RT for BC are demonstrated.
From 2007 to 2008, 250 BC patients referred for postoperative RT were included in a prospective cohort study and followed during the first year after RT. High-resolution computed tomography of the lungs and symptom registration were performed before RT and 3, 6, and 12 months after RT. Patient-reported symptoms were registered by standard quality of life questionnaires. Logistic regression analyses were applied to estimate treatment-related predictors for radiological RP (rRP), clinical RP (cRP), radiological RF (rRF), and clinical RF (cRF).
The occurrence of rRP and cRP at three months was 78% and 19%, while 12 months after RT rRF and cRF was 89% and 16%, respectively; all reported as grade 1. In multivariable analyses, mastectomy predicted cRP at three months (OR = 2.48, p = .03) and cRF at six months, ipsilateral lung volume receiving 20 Gray or more (V20), V30, and mean lung dose (MLD) predicted rRP at six months (OR = 1.06, p = .0003; OR = 1.10, p = .001; and OR = 1.03, p = .01, respectively). Endocrine treatment predicted cRF at 12 months (OR = 2.48, p = .02). Physicians reported significant more dyspnea at 3 months (p = .003) and patients reported ‘a little dyspnea’ more at 3 and 12 months compared to baseline (p = .007).
RP and RF are prevalent in the first year after BC radiation. Mastectomy predicted cRP at three months. V20, V30, D25, and MLD predicted rRP at 6 months, and endocrine treatment predicted cRF at 12 months. Patients and physicians reported dyspnea differently.

放射性肺炎（Radiation pneumonitis, RP）与放射性肺纤维化（Radiation fibrosis, RF）是乳腺癌（Breast cancer, BC）放射治疗（Radiotherapy, RT）后常见的不良反应。然而二者的发生频率存在显著差异。本研究阐述了RP与RF的发生情况及其治疗相关预测因子，并展示了乳腺癌术后放射治疗后第一年内，医师与患者报告的肺部症状表现。

本前瞻性队列研究纳入2007至2008年收治的250例接受术后放射治疗的乳腺癌患者，在放射治疗后第一年内进行随访。分别于放射治疗前、放射治疗后3、6及12个月完成肺部高分辨率计算机断层扫描（high-resolution computed tomography）与症状登记流程。患者报告的症状通过标准化生活质量问卷进行采集。本研究采用logistic回归分析，评估影像学放射性肺炎（radiological RP, rRP）、临床放射性肺炎（clinical RP, cRP）、影像学放射性肺纤维化（radiological RF, rRF）以及临床放射性肺纤维化（clinical RF, cRF）的治疗相关预测因子。

放射治疗后3个月时，rRP与cRP的发生率分别为78%与19%；放射治疗后12个月时，rRF与cRF的发生率分别为89%与16%，所有病例均为1级不良反应。多变量分析结果显示，乳房切除术可预测3个月时的cRP（优势比[OR]=2.48，P=0.03）与6个月时的cRF；患侧肺受照剂量≥20戈瑞（Gray, Gy）的体积（V20）、V30以及平均肺剂量（mean lung dose, MLD）可预测6个月时的rRP（分别对应OR=1.06，P=0.0003；OR=1.10，P=0.001；OR=1.03，P=0.01）。内分泌治疗可预测12个月时的cRF（OR=2.48，P=0.02）。与基线水平相比，医师报告3个月时呼吸困难症状显著加重（P=0.003），患者报告3个月与12个月时“轻度呼吸困难”的比例更高（P=0.007）。

乳腺癌放射治疗后第一年内，RP与RF均较为高发。乳房切除术可预测3个月时的cRP；V20、V30、D25与MLD可预测6个月时的rRP，内分泌治疗可预测12个月时的cRF。患者与医师报告的呼吸困难症状存在差异。