Acute changes in peak expiratory flow rate following palliative radiotherapy for bronchial carcinoma

Changes in respiratory function occurring in the months and years following radiotherapy have been well documented. The changes that occur in the hours after treatment are less clear, we report a study that recorded peak expiratory flow rate (PEFR) in the 72 h following radiotherapy to the mediastinum and large airways.

Fifty-six patients with carcinoma affecting the major bronchii were recruited; 39 were male, with a median age of 66 years; 49 had histologically confirmed lung cancer. The median baseline PEFR was 300 1/s (range: 120-600). Patients were asked to record home PEFR readings in the 72 h that followed the first fraction of radiotherapy. Doses ranges from an 8-Gy single fraction to 60 Gy in 30 fractions.

Forty-nine patients recorded a fall in PEFR (3%-60% of the baseline value) in the 24 h after radiotherapy, the mean for all 56 patients was a fall of 20.3% (95% confidence interval -15.8% to -24.8%). These lowest values occurred a median time of 6 h after treatment (range: 2-24 h). By 72 h the mean PEFR had returned to the baseline. Tumour site (central or lobar bronchus) and fraction size (<3 GY or >3 Gy) had no significant effect on the fall in PEFR (Mann-Whitney U-test P = 0.15 and P = 0.06, respectively).

We conclude that a fall in PEFR can occur after radiotherapy treatment to the mediastinum. This is of concern in patients being treated for bronchial carcinoma whose respiratory function may already be compromised.