Mild Lung Restriction in Breast Cancer Patients after Hypofractionated and Conventional Radiotherapy : a 3-year Follow-up
Mené sur 108 patientes atteintes d'un cancer du sein de stade précoce (âge : 32 à 81 ans ; durée de suivie : 3 ans), cet essai compare les effets d'une radiothérapie conventionnelle et d'une tomothérapie hypofractionnée sur la capacité respiratoire
Purpose : Radiotherapy treatments for early stage breast cancer patients potentially affect the lung parenchyma. Previous studies have shown acute effects on the lung diffusing capacity, essentially due to lung volume restriction. We aimed to assess the effect of radiotherapy on lung function over the course of 3 years. Methods and Materials : Evolution of restrictive and obstructive lung function parameters was investigated in 108 breast cancer participants in a randomized controlled trial comparing conventional radiotherapy (CR) and hypofractionated tomotherapy (TT) (age at inclusion ranging 32-81yr). Spirometry, plethysmography and haemoglobin-corrected diffusing capacity was assessed at baseline, after 3 months, 1, 2 and 3 years. Natural ageing was accounted for by considering all lung function parameters in terms of %predicted values using the most recent reference values for women up to 80 years. Results : In the patients with negligible history of respiratory disease or smoking (n=77), the greatest rate of functional decline was observed during the initial 3 months, this acute decrease being more marked in the CR vs the TT arm. During the remainder of the 3-year follow-up period, values (in terms of %predicted) were maintained (diffusing capacity) or continued to decline at a slower rate (forced vital capacity). However, the average decline of the restrictive lung function parameters over a 3-year period did not exceed 9%predicted in either TT or CR arm. Obstructive lung function parameters remained unaffected throughout. Including also the 31 patients with a history of respiratory disease or more than 10 packyears showed a very similar restrictive pattern. Conclusions : In women with breast cancer, both conventional radiotherapy and hypofractionated tomotherapy induce small but consistent restrictive lung patterns over the course of a 3-year period, irrespective of baseline respiratory status or smoking history. The fastest rate of lung function decline generally occurred in the first 3 months.