Table 1. Characteristics of all included studies (basic information).
| Author & year | Region | Study design | Anti-cancer treatments | NSCLC | DM | |
|---|---|---|---|---|---|---|
| Overall | Stage IIIb–IV (%) | |||||
| Tan B 2011 (11) | China | Retrospective cohort study | Chemotherapy | Advanced, inoperable | 59 (79.7) | Yes |
| Ahmed I 2015 (12) | USA | Retrospective cohort study | Chemoradiotherapy | Locally advanced, inoperable | 21 (40.0) | Yes |
| Sayed R 2015 (13) | Egypt | Randomized controlled trial | Chemotherapy | Stage IV | 30 (100.0) | No |
| Chen H 2015 (14) | China | Retrospective cohort study | EGFR-TKI | Advanced, inoperable | 84 (93.3) | Yes |
| Lin J 2015 (15) | USA | Retrospective cohort study | Chemotherapy† | Stage IV | 349 (100.0) | Yes |
| Wink K 2016 (16) | Netherlands | Retrospective cohort study | Chemoradiotherapy | Locally advanced, inoperable | NG§ | Yes |
| Arrieta O 2016 (17) | Mexico | Retrospective cohort study | Chemotherapy/TKI | Advanced, inoperable | 174 (93.5) | Yes |
†, in this study, there were other treatments for lung cancer instead of chemotherapy, in order to improve consistence of the baseline among all included studies, we selected data only based on chemotherapy; §, the study demonstrated 644 (94.4%) patients with stage III (no stage IV), but did not separate the data into stage IIIa and stage IIIb. NSCLC, non-small cell lung cancer; EGFR, epidermal growth factor receptor; TKI, tyrosine kinase inhibitors; NG, not given; DM, diabetes mellitus.