Respiratory function changes after chemotherapy: An additional risk for postoperative respiratory complications?

Background. Patients receiving chemotherapy for lung cancer usually modify their lung function during treatment with increases in forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) and decreases in lung diffusion for carbon monoxide (DLCO). This prospective study was designed to evaluate functional changes in forced expiratory volume in 1 second, forced vital capacity, and DLCO after three courses of induction chemotherapy with cisplatinum and gemcitabine in stage IIIa lung cancer patients and to assess their impact on respiratory complications after lung resection. Methods. From March 1998 to January 2001, 30 consecutive patients with N2 nonsmall cell lung cancer had surgical resection after neoadjuvant treatment. Prechemotherapy and postchemotherapy results of standard respiratory function tests and DLCO were compared in patients with and without postoperative respiratory complications. Results. All 30 patients completed the chemotherapy protocol without respiratory complications. Significant improvements (p<0.05) were recorded after chemotherapy in transition dyspnea score, Pao(2) (mean value from 79.8 to 86.4 mm Hg), forced expiratory volume in 1 second % (from 78.1% to 87.5%) and forced vital capacity % (from 88.1% to 103.3%). Lung diffusion for carbon monoxide was significantly impaired after chemotherapy (from 74.1% to 65.7%; p=0.0006), as well as DLCO adjusted for alveolar volume (from 92.8% to 77.4%; p<0.0001). One patient died after surgery and 4 patients (13.3%) experienced postoperative respiratory complications. Compared with patients without complications, these 4 patients had higher mean increase in FEV1 after chemotherapy (+26.8% vs + 6.7%; p=0.025), but greater mean decrease in DLCO/Va (-27.8% vs -13.6%; p=0.03). Impact of change in DLCO on postoperative respiratory complications was not confirmed by multiple logistic regression analysis (p=0.16). Conclusions. In lung cancer patients, forced expiratory volume in 1 second and forced vital capacity assessed after neoadjuvant chemotherapy are not reliable indicators of the likelihood of respiratory complications after surgery. The risk of respiratory complication may be directly linked to loss of DLCO/Va. Lung diffusion for carbon monoxide assessed after neoadjuvant chemotherapy is probably the most sensitive risk indicator of respiratory complications after surgery. We recommend that DLCO studies be performed before and after chemotherapy in lung cancer patients undergoing induction therapy.