BACKGROUNDAdverse effects of paclitaxel and carboplatin have been well described; however, pulmonary toxicity after patients receive this regimen has not been investigated extensively.METHODSTo clarify this issue, 33 consecutive patients who were treated with paclitaxel and carboplatin underwent prospective evaluation of respiratory function, which included pulmonary symptoms, pulmonary function tests (PFTs), arterial blood gas levels, and radiographic studies. Assessment was performed before and after completion of chemotherapy in all patients. Patients with substantial declines in PFTs, defined as a decline ≥ 20 percent in forced expiratory volume in 1 second (FEV1), total lung capacity (TLC), or diffusion capacity for carbon monoxide (DLCO), were reassessed 5 months later.RESULTSAfter chemotherapy, there were no significant changes in forced vital capacity (FVC; 111% ± 21% of the predicted value before chemotherapy vs. 111 ± 20% of the predicted value after chemotherapy), FEV1 (108% ± 24% of the predicted value before chemotherapy vs. 107% ± 22% of the predicted value after chemotherapy), FEV1/FVC ratio (79% ± 8% before chemotherapy vs. 78% ± 6% after chemotherapy), alveolar volume (VA; 95% ± 14% of the predicted value before chemotherapy vs. 96% ± 14% of the predicted value after chemotherapy), or TLC (96% ± 14% of the predicted value before chemotherapy vs. 97% ± 13% of the predicted value after chemotherapy). In contrast, there was a significant decline in DLCO (101% ± 20% of the predicted value before chemotherapy vs. 96 ± 21% of the predicted value after chemotherapy; P < 0.05). Arterial blood gas levels did not change after treatment. No patient had decreased FEV1 or TLC levels by ≥ 20%, whereas 4 of 33 patients (12%) exhibited a substantial decline (≥ 20%) in DLCO that persisted 5 months after treatment (DLCO at baseline, immediately after chemotherapy, and 5 months after the completion of chemotherapy, respectively: 99% ± 36% of the predicted value vs. 75% ± 28% of the predicted value vs. 74% ± 31% of the predicted value; P < 0.05). None of the 33 patients developed respiratory symptoms or had radiologic signs suggestive of lung toxicity. Among the various risk factors examined, baseline DLCO and FEV1 levels were associated with changes in DLCO post‐treatment.CONCLUSIONSThis prospective analysis showed that the combination of paclitaxel with carboplatin induced an isolated decrease in DLCO level in the absence of clinical or radiologic evidence of toxicity. Further studies are needed to clarify whether this reduction in DLCO is predictive of subsequent pulmonary impairment. Cancer 2002;94:452–8. © 2002 American Cancer Society.