背景與目的：肺癌無論在全世界或台灣都是導致癌症病人死亡的主要原因之一，許多肺癌病患會因為共病性的緣故而影響其存活率。這項回朔性研究是利用台灣全民健保資料庫建立的研究族群來探究肺癌病人的共病性危險因子。方法：全民健康保險（NHI）為一項強制性的全民醫療保險計畫，可提供台灣居民全面的醫療服務。本研究使用2000年承保抽樣歸人檔（LHID 2000）分別出有無罹患肺癌的組別。肺癌共病性的風險評估是透過比較有無其他疾病的肺癌病患之勝算比值（odds ratios）。結果：本研究包含3,799位肺癌病例組及15,196位對照組。分析結果顯示，肺癌病例組與多種肺部疾病及其他系統性疾病，如：胃和十二指腸潰瘍、肝膽胰疾病、細菌感染及菌血症等皆有較高的共病性（P<0.05）。此外，勝算比值分析結果亦顯示女性肺癌病人有胸膜炎的共病性風險要高於男性（OR=9.33 vs. 4.69; P<0.001）。結論：研究結果顯示肺癌的共病性風險並不僅限於肺部疾病而已，亦會與其他的器官及系統疾病相關。未來仍須利用更多族群樣本的分析來確認此研究結果。

Background and Purpose: Lung cancer is the leading cause of cancer-related deaths in the world and Taiwan. Many lung cancer patients have comorbidities that significantly affect their overall survival. This retrospective study was conducted to investigate the comorbidity risk factors of systemic diseases for lung cancer patients by using Taiwan’s nationwide, population-based database. Methods: All public insurance systems were placed under the universal National Health Insurance (NHI) program to ensure all Taiwan residents receive adequate health care. We searched the Longitudinal Health Insurance Database 2000 (LHID 2000) for the source population to identify the patients with lung cancer or not. The risk of lung cancer was estimated by calculating odds ratios (ORs) for patients with various comorbidities compared with patients without comorbidities. Results: A total of 3,799 cases of lung cancer were defined as study group, and a total of 15,196 subjects were identified as the control group. The lung cancer cohort had a high prevalence of pulmonary diseases and other systemic diseases, including gastric and duodenal ulcers, hepatobiliary and pancreatic disease, bacterial infections, and bacteremia (P < 0.05). In addition, the OR analysis showed that the sex-specific risk of lung cancer in the pleurisy stratification was higher in women than in men (OR =9.33 vs. 4.69; P< 0.001). Conclusion: Our results showed that significant comorbidity risk factors for lung cancer are not only related to pulmonary diseases but also in other organs or systems. Additional studies, especially population- based studies, are suggested to confirm these observations.