Long-term functional and radiological pulmonary changes after radiation therapy for breast cancer
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Background. We assessed late functional and radiological pulmonary changes in breast cancer patients after a median of 11 years following radiotherapy (RT).
Material and methods. Seventy women who received adjuvant loco-regional RT for breast cancer during November 1994–May 1998 accepted to participate in this follow-up study. Pulmonary function tests (PFTs) (n = 56) were compared to pre-RT examinations and diagnostic computer tomography (CT) of the lungs (n = 70) were performed and compared to four months post-RT examinations.
Result. The median-matched vital capacity (VC), forced expiratory volume in one second (FEV1), and total lung capacity (TLC) were reduced 15%, 9%, and 7%, respectively, at the long-term follow-up (p < 0.001). We could not, however, detect a correlation between ipsilateral V20 and VC-changes. Diffusion capacity (DLCO) appeared to improve compared with the pre-RT baseline level probably due to transient chemotherapy-induced toxicity. The median-matched percentage of the predicted DLCO 11 years after RT was, however, only 86%, indicating a chronic therapy-induced reduction also of this metric. According to the Arriagada classification, ipsilateral V20 and long-term CT-changes showed a significant correlation (rs: 0. 57; p < 0.001) in a small subset of the women.
Conclusion. A chronic clinically significant reduction of PFTs compared to pre-RT values and CT-changes four months after RT were still detectable after a median follow-up of 11 years. There was a statistical correlation between V20 and abnormalities on CT but no statistical correlation between V20 and VC-changes.