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Interact CardioVasc Thorac Surg 2008;7:1001-1006. doi:10.1510/icvts.2007.173955 © 2008 European Association of Cardio-Thoracic Surgery
Recent results regarding the clinical impact of smoking history on postoperative complications in lung cancer patientsDivision of Thoracic and Cardiovascular Surgery, Department of Surgery, Kawasaki Medical School, 577 Matsushima, Kurashiki Okayama 701-0192, Japan Received 19 December 2007; received in revised form 16 July 2008; accepted 17 July 2008
Corresponding author. Tel.: +81-86-462-1111; fax: +81-86-462-1199.
Cigarette smoking is a well-known risk factor for perioperative surgery-related complications; however, steady progress in perioperative management has been made year by year. This study investigated the influence of cigarette smoking on postoperative complications in patients with lung cancer over the last three years in our institution. Clinical records of 194 patients who had undergone a pulmonary resection for lung cancer were retrospectively reviewed. The clinico-pathological findings and postoperative complications were compared among patients with smoking history. Smokers, including a higher number of men, had more preoperative respiratory complications, a lower FEV1/FVC, larger tumors, and included more squamous cell carcinoma in comparison to non-smokers. A univariate analysis revealed that sex, age and smoking history were independent risk factors in the postoperative complications; however, a multivariate analysis revealed that those factors including smoking history were not independent. In a subgroup of smokers subclassified by their smoking status or smoking index, there were no significant differences in postoperative complications. Over the recent three years of this study, smoking history was not a significant risk factor in postoperative complications. Especially in smokers, smoking status or smoking index was not a significant risk factor in postoperative complications, too.
Key Words: Smoking; Smoking status; Smoking history; Lung cancer; Postoperative complications
Lung cancer is a major cause of death in many developed countries. A surgical resection continues to play an important role, especially in the earlier stages of lung cancer. Tobacco smoke-derived toxins are highly associated with the development of lung cancer, and the increasing mortality due to lung cancer is significantly associated with the increased number of smokers [1, 2]. Recently, several reports demonstrated the smoking status to be a significant prognostic factor for lung cancer [3, 4]. Smoking has been found to be a risk factor for the development of postoperative complications after many types of surgery, even in the absence of chronic lung disease. The relative risk of complications after surgery for smokers compared to non-smokers has been reported to increase from 1.2-fold to 5.5-fold [5, 6]. Generally, smoking is a serious risk factor in anesthesia, as well. Smokers have a higher prevalence of chronic bronchitis than non-smokers (23.3% vs. 4.8%). The incidence of perioperative respiratory events occurred in 5.5% with smokers and in 3.1% with non-smokers [7]. However, improvements in perioperative management have been made year by year. Such improvements are therefore expected to result in a decreased incidence of postoperative complications. In this study, the relationship between cigarette smoking and postoperative complications after surgery was retrospectively investigated to clarify the effect of cigarette smoking on postoperative complications in lung cancer patients.
A total of 194 patients who underwent a pulmonary resection for lung cancer between January 2003 and December 2006 at the Kawasaki Medical School Hospital were retrospectively studied. The clinico-pathological findings and postoperative complications were compared among patients with smoking history. An anatomic pulmonary resection is normally administered for lung cancer. This includes video-assisted thoracic surgery (VATS) for lobectomy and segmentectomy for clinical stage IA. A standard resection including pneumonectomy and lobectomy (n=146) included 85 cases by muscle sparing thoracotomy and 60 cases by VATS. A lesser resection including segmentectomy and wedge resection (n=48) included 21 cases by muscle sparing thoracotomy and 27 cases by VATS. Neoadjuvant preoperative therapy has not been used except for superior sulcus tumor cases. The preoperatively collected data included gender, age, smoking status, the pack-year index (PYI), preoperative respiratory complications, serum carcinoembryonic antigen (CEA) level, forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1). The postoperative data included the type of resection (standard resection including lobectomy, or lesser resection including segmentectomy and wedge resection), duration of insertion of the chest tube, as well as postoperative complications. Postoperative complications were defined as the development of one or more of the following events: (1) pneumonia defined by new radiographic infiltration with fever, treated using antibiotics; (2) atelectasis requiring a bronchoscopy; (3) an air leak requiring intercostal tube drainage for >7 days; (4) a bronchopleural fistula with a large air leak or infection; and (5) a cardiac event including arrhythmia. In this study, the ‘smoking history’ was defined by two criteria. One was the ‘smoking status’, while the other was the ‘smoking index’. Non-smokers were those with a lifetime exposure to no cigarettes, current smokers were those who had smoked within 12 months at the time of diagnosis, and ex-smokers were those who had quit smoking more than 12 months before diagnosis [8, 9]. The smoking index was classified by the PFI as the number of cigarette packs (20 cigarettes per pack) consumed a day multiplied by years. A variety of analyses were performed to determine the effect of the smoking status and smoking index on postoperative complications in the three years prior to study and to evaluate the risk factors for such complications following a pulmonary resection for lung cancer.
Statistical analysis for differences in significance among the categorized groups and any correlation between the risk factors and the occurrence of complications were performed with Fisher's exact test or
The patients were classified as follows; (1) Smoking status: there were 70 non-smokers, 40 ex-smokers, and 84 current smokers. (2) Smoking index: PYI: 70 patients were 0, 55 were <40, and 69 were 40 or more. Postoperative complications occurred in 34 patients (17.5%). The only postoperative death was caused by acute respiratory distress syndrome (ARDS) from a bronchopleural fistula to pneumonia. 3.1. Analysis of smokers and non-smokers Clinical characteristics, surgical treatments, and pathologic stages are summarized in Table 1. Smokers, which included a higher number of men (P<0.0001), had more preoperative respiratory complications (P=0.001), had a lower FEV1/FVC (P<0.0001), had a larger tumor (P=0.009), and a higher incidence of squamous cell carcinoma (P<0.0001) in comparison to non-smokers. The two groups were fairly similar with respect to surgical procedures and the pathological stage.
Postoperative complications are presented in Table 2. Smokers had a significant differences in postoperative complications (P=0.038) and significant longer duration of chest tube (P=0.016) in comparison to non-smokers. Smokers had a significant differences in postoperative complications in standard resection group (P=0.033), but not significant in lesser resection group (P=0.682) in comparison to non-smokers.
A univariate analysis revealed that sex (P=0.032), age (P=0.041), and smoker (P=0.038) were independent risk factors in the postoperative complications; however, a multivariate analysis revealed that those factors including being a smoker were not independent (Table 3).
3.2. Analysis based on smoking status The clinical characteristics, surgical treatment, and pathologic stage are summarized in Table 4. In comparison to ex-smokers, current smokers were younger (P=0.032) but had no significant risk factors including preoperative respiratory complications and FEV1/FVC. The two groups were fairly similar with respect to tumor size, histological type, the surgical procedures and pathological stage.
Postoperative complications are presented in Table 5. Current smokers had no significant differences in either the postoperative complications or chest tube duration in comparison to ex-smokers.
3.3. Analysis based on smoking index Clinical characteristics, surgical treatment, and pathologic stage are summarized in Table 6. Smokers with a PFI index of 40 or more, who included a higher number of men (P=0.004), had a lower FEV1/FVC (P=0.042) in comparison to those with a PFI index of <40. The two groups were fairly similar with respect to surgical procedure and pathological stage.
Postoperative complications are presented in Table 7. Smokers with a PFI index of 40 or more had no significant differences in postoperative complications and chest tube duration in comparison to those with a PYI index of <40.
This study examined the postoperative course of recent patients undergoing a pulmonary resection for lung cancer and evaluated the significance of preoperative variables as indicators of postoperative risk, especially smoking. The postoperative complication rate was quite low. The indicators of patients at high risk for the development of complications were age, sex, and smokers in a univariate analysis, but that was not significant in a multivariate analysis. In previous studies, risk factors for postoperative complications after lung resection were found to be male sex, old age, restricted cardiopulmonary reserve, the need for a pneumonectomy, extent of surgery, predicted postoperative FEV1, chronic obstructive pulmonary disease, a poor nutritional status, and FEV1 [10–12]. Two studies have specifically addressed the link between smoking and thoracic surgery. Nakagawa et al. [13] reported that five perioperative factors, i.e. sex, age, smoking status, FEV1/FVC<70% and operation time were identified as risk factors for postoperative complications. Therefore, current smokers (within 2 weeks cessation) and recent smokers (within 2–4 weeks cessation) had a higher risk in comparison to non-smokers, although they did not reach statistical significance in the multivariate analysis. In contrast, the risk in ex-smokers (over 4 weeks cessation) was comparable to that in the non-smokers. Barrera et al. [14] showed that there was a significant difference in pulmonary complications between non-smokers and all smokers, but no difference among the subgroups of smokers, including past (over 8 weeks cessation), recent (within 8 weeks cessation), and ongoing smokers. In addition, the independent risk factors were a lower DLCO and primary lung cancer rather than metastatic disease. The current report is consistent with the two previous reports. There are several possible explanations for the low rate and lack of differences between smokers and non-smokers for postoperative complications. 1) The detection of early stage cancer is increasing with the development of CT screening which allows a use of minimally invasive surgical techniques through VATS; 2) For a similar reason, the percentage of pneumonectomy and extended surgery cases has markedly decreased; 3) Perioperative management, including anesthesia, surgical techniques, and cardio-respiratory management, has improved; 4) Many of the outpatients with a smoking history undergo detailed pulmonary function tests to decide the proper treatment; Specifically, in low pulmonary function patients, respiratory training and administration of tiotropium are applied for improvement of pulmonary function [15]. We believe that, because of a number of these factors, smoking history has not had any significant impact on the postoperative complications in recent years, and that patients with a smoking history could safely undergo pulmonary resection. There are several limitations for this study. First, all of the clinical analyses were performed retrospectively, and the sample size was small. Second, we relied on a questionnaire for the determination of smoking status and did not obtain chemical confirmation. In summary, recent postoperative complication rates in the treatment of lung cancer are quite acceptable. In comparison to non-smokers, smoking patients did not have a higher rate of postoperative complications, including pneumonia and air leakage. Based on these findings in a small sample size, pulmonary resection is possible as a safe treatment in smoking patients with lung cancer. Perioperative management strategies, including anesthesia, surgical techniques, and cardio-respiratory management have improved. Furthermore, proper management of the patients is therefore required to improve the future outcome.
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Abstract
1. Introduction
2-test when appropriate. The test used for the comparison of continuous data is unpaired t-test. Multivariate analyses were performed using a logistic regression analysis. All data were analyzed using the Stat View software program 5.0 (SAS Institute Inc., Cary, NC). All statistical tests were two-sided, and P<0.05 was regarded as statistically significant.