Prolonged progression-free survival and overall survival are associated with diabetes mellitus but inversely associated with levels of blood glucose in patients with lung cancer

BACKGROUND: Previous studies have provided conflicting evidence about the increased overall survival (OS) in lung cancer patients with diabetes mellitus (DM) compared with those without DM. This study assessed progression-free survival (PFS)/OS in lung cancer patients with or without DM and tentatively analyzed the impact of blood glucose levels on PFS/OS in lung cancer patients. METHODS: Data were collected from lung cancer patients based upon admission records from January 2010 to January 2012 and follow-up records from January 2010 to January 2015 in the Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai. The data included patient sex, age, body mass index (BMI), smoking status, history of DM, level of blood glucose, pathological type, clinical stage of cancer, chemotherapy regimen, and history of anti-DM drugs. The Cox regression model and Kaplan-Meier method were used for the analysis of hazard factors and PFS/OS. For comparison of PFS/OS in lung cancer with or without DM, patients were divided into three groups: lung cancer with DM, lung cancer without DM but with elevated level of blood glucose, lung cancer without DM or elevated level of blood glucose. RESULTS: In total, the data from 200 lung cancer patients (138 males/62 females, aged 29.0 to 78.0 years, mean 60.0 ± 8.6 years) were collected. For the comparison of PFS/OS in lung cancer patients with or without DM, patients were divided into three groups: lung cancer with DM (n = 31); lung cancer without DM but with elevated levels of blood glucose (n = 40); and lung cancer without both DM and elevated levels of blood glucose (n = 128), whereas 1 patient dropped out of the study. All the patients underwent complete chemotherapy and were followed up for 36.0 to 60.0 months. Kaplan-Meier survival analysis showed that lung cancer patients with DM had increased PFS and OS compared with those without DM (log-rank, P < 0.05, P < 0.01); the median PFS in lung cancer with DM was 12.0 months (95% confidence interval [CI], 4.0–16.0) vs. 6.0 months in those without DM (95% CI, 5.8–6.3); and the median OS in lung cancer patients with DM was 37.0 months (95% CI, 29.0–46.6) vs. 12.0 months in those without DM (95% CI, 10.9–13.1). For the other two groups of patients without DM, there was a trend toward a shorter PFS and OS in patients with elevated blood glucose compared with those without elevated blood glucose. Cox regression showed that PFS in lung cancer patients was favorably associated with the usage of anti-DM drugs, BMI, clinical stage of cancer, and chemotherapy regimen (all P < 0.05) but was inversely associated with the level of blood glucose (P < 0.05). CONCLUSIONS: Lung cancer patients with DM have prolonged PFS and OS compared with those without DM, and the level of blood glucose was inversely associated with PFS. The current results indicate that PFS may be a meaningful intermediate endpoint for OS and that the levels of blood glucose hopefully represent a prognostic factor in lung cancer patients.