329P - Pulmonary function and lung fibrosis up to 12 years after breast cancer radiotherapy

Background

Breast cancer (BC) radiotherapy (RT) may induce lung damage ranging from radiological changes only to respiratory failure. The evidence of long-term radiation fibrosis (RF) and its impact on lung function and patients reported dyspnea is scarce. The aim of the present study was to evaluate lung function from before RT to up to 12 years after treatment and identify predictors for long-term RF and reduced lung function.

Methods

BC patients (n=250) referred to postoperative RT (2 Gy x 25) were enrolled in a prospective cohort study from February 2007 to October 2008. All assessments were conducted through clinical controls before RT (baseline), at 3, 6 and 12 months and at long-term follow- up ranging from 7-12 years after RT. Lung function was assessed by the pulmonary function tests (PFT) Vital capacity (VC), Forced Expiratory volume in 1second (FEV1), Forced Vital Capacity (FVC) and diffusion capacity for carbon monoxide (DLCO). RF was diagnosed by High Resolution Computer Tomography scans and graded in accordance with the CTCAE version 3.0 criteria. Patient reported dyspnea was assessed by the EORTC QLQ-C30.

Results

VC, FVC, FEV1 and DLCO declined at 3 months after RT and remained low at long-term follow-up except for DLCO which increased up to 12 years after RT. VC, FEV1, and FVC changes from baseline differed between patients treated with chemotherapy and those not treated with chemotherapy. FEV1 changes from baseline differed between locoregional and local radiated patients. A decline in VC, FEV1, and FVC 3 months after RT predicted a decline in PFT up to 12 years (p=0.020, p=0.004, and p=0.020, respectively). At long-term follow-up age was the only patient and treatment-related factor associated with RF (p=0.021). RF was observed in 144 patients (91%), of which 129 (81%) had fibrosis Grade 1 and 15 (9%) had fibrosis Grade 2. 61 (35%) patients reported dyspnea, mainly grade 1.

Conclusions

Pulmonary function deteriorated in the first year and up to 12 years after BC RT. An early decline in VC, FVC and FEV1 predicted further decline at long-term follow-up. RT. Chemotherapy and locoregional RT predicted a decrease in PFT in the first year and for up to 12 years after RT. Older age was associated with RF at long-term follow-up. Few patients reported severe dyspnea.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The Norwegian University of Science and Technology, Faculty of Medicine.

Funding

The Liaison Committee for education, research and innovation in Central Norway.

Disclosure

All authors have declared no conflicts of interest.