Changes in pulmonary function up to 10 years after locoregional breast irradiation.

PURPOSE: To evaluate the long-term impact of locoregional breast radiotherapy (RT) on pulmonary function tests (PFTs). METHODS AND MATERIALS: This study included 75 women who underwent postoperative locoregional breast RT. PFTs were performed before RT and 3, 6, and 12 months and 8 to 10 years after RT. By use of univariate and multivariate analyses, the impact of treatment- and patient-related factors on late changes in PFTs was evaluated.
RESULTS: During the first year after RT, all PFTs significantly worsened at 3 to 6 months after RT (p < 0.05). At 12 months, forced vital capacity (FVC), vital capacity (VC), and forced expiratory volume in 1 second (FEV(1)) recovered almost to baseline values, whereas total lung capacity (TLC) and diffusion capacity of carbon monoxide (DL(CO)) recovered only slightly and were still found to be decreased compared with baseline (p < 0.05). At 8 to 10 years after RT, mean reductions in FEV(1) of 4% (p = 0.03) and in VC, DL(CO), and TLC of 5%, 9%, and 11% (all p < 0.0001), respectively, were observed compared with pre-RT values. On multivariate analysis, tamoxifen use negatively affected TLC at 8 to 10 years after RT (p = 0.033), whereas right-sided irradiation was associated with a late reduction in FEV(1) (p = 0.027). For FEV(1) and DL(CO), an early decrease was predictive for a late decrease (p = 0.003 and p = 0.0009, respectively).
CONCLUSIONS: The time course of PFT changes after locoregional RT for breast cancer follows a biphasic pattern. An early reduction in PFTs at 3 to 6 months with a partial recovery at 12 months after RT is followed by a late, more important PFT reduction up to 8 to 10 years after RT. Tamoxifen use may have an impact on this late decline in PFTs.