Multiple primary cancers involving lung cancer at a single tertiary hospital: Clinical features and prognosis

Background: The development of other primary cancers in patients with lung cancer is unfortunate and uncommon, although the frequency is increasing. The aim of this study was to determine the clinical features and prognosis in patients with multiple primary cancers (MPC) involving lung cancer. Methods: After a retrospective review of 1644 patients who were newly diagnosed with primary lung cancer between 1998 and August 2012 at a tertiary hospital, 105 patients were included. Results: The median age at the time of lung cancer diagnosis was 67 years, and 68 patients were male. Synchronous primary cancers occurred in 47% of the study population (49/105). Among those with metachronous cancer (56/105), the median interval between the diagnosis of lung cancer and another malignancy was 47.1 months; 21 patients were diagnosed with lung cancer as the first primary tumor. The most frequent type of other malignancy was urogenital (30%), followed by gastrointestinal (30%) and thyroid malignancies (16%). Advanced stage of lung cancer (hazard ratio (HR), 3.2; 95% confidence interval (CI), 1.8-5.7; P < 0.001), supportive care only as treatment for lung cancer (HR, 2.8; 95% CI, 1.3-6.0; P = 0.006), and head and neck cancer as another malignancy (HR, 3.9; 95% CI, 1.4-10.8; P = 0.010) were independent predictors of shorter survival from the time of diagnosis of the second primary cancer. Conclusion: Advanced lung cancer stage, symptomatic supportive care only without antitumor therapy for lung cancer, and head and neck cancer as another primary malignancy were poor prognostic factors in patients with MPC involving primary lung cancer.