Study of functional and biochemical indicators of subclinical lung damage in bleomycin-treated patients

Abstract

In 30 patients affected by testicular non-seminomatous cancer we evaluated pulmonary function tests before and after bleomycin-including combination chemotherapy. We paid particular attention to changes in diffusing lung capacity (DCO) and its two components, namely diffusing capacity of the alveolar-capillary membrane (Dm) and pulmonary capillary blood volume (Vc). In the same patients we also evaluated the behaviour of serum procollagen III aminopeptide (sP-III-P), assumed to be a biochemical equivalent to Dm, and of serum angiotensin converting enzyme (S-ACE), assumed to be a biochemical equivalent to Vc. We found that, after chemotherapy, patients showed a significant decline in several pulmonary function parameters, namely VC, TLC, and FEV1 (P < 0.0001, P = 0.0351, P = 0.0004, respectively), when compared to pre-treatment values. DCO was significantly impaired after chemotherapy (P < 0.0001), but with regard to its components, Vc values showed a significant decline (P = 0.0002), whereas Dm values were unchanged. Values of sP-III-P raised significantly after chemotherapy (P = 0.003), whereas S-ACE activity did not show any significant variation. When we looked at relationships between functional and biochemical parameter variations, the only significant correlation we found was between DCO and S-ACE (r2 = 0.112; P < 0.02). We conclude that in asymptomatic patients treated by bleomycin-including combination chemotherapy, DCO impairment is likely to occur because of a subclinical injury to pulmonary vessels, as suggested by Vc decline. Although the occurrence of pulmonary interstitial fibrosis after chemotherapy was excluded by chest X-ray examination and by stable values of Dm, sP-III-P elevation would suggest an accelerated type III collagen turnover in interstitial fibroblasts activated by bleomycin.