PURPOSE: There are anecdotal reports of patients with COPD who experience symptomatic improvement following radiation treatment but the mechanisms remain unknown. We present a case of a patient with severe COPD who underwent radiation for a malignant lung nodule and showed marked improvement in dyspnea and exercise tolerance.
METHODS: CT scanning in a 70 year-old woman with severe COPD (FEV1=34%predicted) fortuitously identified a suspicious spiculated nodule in her right middle lobe. Subsequent PET demonstrated that she likely had primary lung cancer (stage Ia). Tissue diagnosis or surgery was not attempted given the location of the nodule and her fragile respiratory status. Radical radiation treatment was undertaken. The patient performed pulmonary function and cardio-pulmonary exercise testing following radiation treatment. Results were compared with pre-treatment baseline values.
RESULTS: Radiotherapy caused a significant reduction in static lung hyperinflation: total lung capacity, functional residual capacity and residual volume decreased by 14, 24 and 40%, respectively and inspiratory capacity, FEV1 and forced vital capacity increased by 49%, 58% and 63%, respectively. Lung diffusion capacity decreased by 27%. Compared with baseline exercise: 1) dyspnea ratings were uniformly lower and the primary locus of sensory limitation changed from breathing difficulty to leg discomfort; 2) peak work rate and oxygen uptake increased by 20 watts (67%) and 4.1 ml/kg/min (37%), respectively; 3) The ventilatory equivalents for O2 and CO2 decreased throughout exercise indicating improved efficacy of ventilation. Eight months after treatment her Medical Research Council rating went from IV to II and she claimed that the treatment had given her ‘a new life.’
CONCLUSIONS: Our patient showed marked improvement in dyspnea and exercise tolerance following radiation treatment. Physiological testing revealed potential contributory factors to reduced dyspnea which included: substantial lung volume reduction and reduced ventilatory requirements.
CLINICAL IMPLICATIONS: It is conceivable that in selective patients with extensive lung hyperinflation and emphysema, radiation-induced alterations in the elastic properties of the lung and in ventilation-perfusion mismatching may actually have favourable effects on dyspnea and exercise tolerance.
DISCLOSURE: The following authors have nothing to disclose: Jordan Guenette, Natya Raghavan, Paloma O’Meara, Naparat Amornputtisathaporn, Catherine deMetz, Robert Nolan, Denis O'Donnell
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