Table 1.
Characteristics of Included Studies (n = 36).
| First Author | Year | Journal | Country | Design | Data Source | Comparator | Matched | N | Adjusted Analysis | Stages |
|---|---|---|---|---|---|---|---|---|---|---|
| Cannon | 2017 | Head & Neck | USA | Retrospective Cohort | SEER | Yes | No | 5856 | Yes | III-IV |
| Crombie | 2012 | Oral Oncology | Australia | Retrospective Cohort | Chart Review | No | No | 54 | No | I-IV |
| Ellis | 2017 | Otolaryngology Head & Neck Surgery | USA | Retrospective Cohort | NCDB | Yes | Yes | 1912 (matched); 20779(unmatched) | Yes | I-II |
| Fujiwara | 2017 | Oral Oncology | USA | Retrospective Cohort | NCDB | Yes | No | 23,459 | Yes | I-IV |
| Gogarty | 2017 | European Archives of Oto-Rhino-Laryngology | Ireland | Retrospective Cohort | National Cancer Registry Ireland (NCRI) | Yes | No | 397 | Yes | I-II |
| Gore | 2014 | Head & Neck | Australia | Retrospective Cohort | Unspecified Cancer Database | Yes | No | 104 | Yes | I-IV |
| Hauswald | 2012 | Acta Oncologica | Germany | Retrospective Cohort | Chart Review | Yes | No | 66 | No | I-IV |
| lyer | 2015 | Cancer | Singapore | Randomized Controlled Trial | N/A | Yes | N/A | 119 | No | III-IV |
| Jenwitheesuk | 2010 | Journal of the Medical Association of Thailand | Thailand | Retrospective Cohort | Chart Review | Yes | No | 107 | No | I-IV |
| Kjems | 2015 | International Journal Radiation Oncology, Biology, Physics | Denmark | Retrospective Cohort | Chart Review | No | No | 942 (100 OSCC) | No | I-IV |
| McDowell | 2014 | Oral Surgery, Oral Medicine, Oral Pathology, and Oral Radiology | Australia | Retrospective Cohort | Chart Review | Yes | No | 31 | Yes | T4 |
| Pederson | 2011 | American Journal of Clinical Oncology | USA | Prospective Cohort | Chart Review | No | No | 21 | No | II-IV |
| Scher | 2015 | Oral Oncology | USA | Retrospective Cohort | Chart Review | No | No | 73 | No | I-IV |
| Sowder | 2017 | Head & Neck | USA | Retrospective Cohort | SEER | Yes | No | 8274 | Yes | I-II |
| Spiotto | 2017 | JAMA Otolaryngology | USA | Retrospective Cohort | NCDB | Yes | Yes | 2286 (matched); 6900(unmatched) | Yes | III-IV |
| Stenson | 2010 | The Laryngoscope | USA | Retrospective Cohort | Chart Review | No | No | 138 | No | III-IV |
| Studer | 2012 | Radiation Oncology | Switzerland | Retrospective Cohort | Chart Review | Yes | No | 160 | No | I-IV |
| Wang | 2010 | Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology | Taiwan | Retrospective Cohort | Chart Review | Yes | No | 88 | No | I-IV |
| Bossi | 2014 | Annals of Oncology | Italy | Randomized Controlled Trial | N/A | Yes | N/A | 198 | Yes | T2-T4 |
| Chinn | 2014 | JAMA Otolaryngology | USA | Prospective cohort | Chart Review | Yes | Yes | 72 | Yes | III-IV |
| Harada | 2013 | Cancer Chemotherapy and Pharmacology | Japan | Non-Randomized Trial | N/A | No | No | 39 | No | III-IV |
| Hauswald | 2012 | Acta Oncologica | Germany | Retrospective Cohort | Chart Review | Yes | No | 66 | No | I-IV |
| Hirakawa | 2017 | Japanese Journal of Clinical Oncology | Japan | Retrospective Cohort | Chart Review | Yes | No | 164 | Yes | I-IV |
| Inhestern | 2017 | Annals of Oncology | Germany | Non-Randomized Trial | N/A | No | No | 59 | Yes | I-IV |
| Irjala | 2012 | European Archives of Oto-Rhino-Laryngology | Finland | Retrospective Cohort | Chart Review | No | No | 10 | No | I-IV |
| Kies | 2012 | Head & Neck | USA | Non-Randomized Trial | N/A | No | No | 23 | No | T2-3 N0-2 |
| Kina | 2016 | Cancer Chemotherapy and Pharmacology | Japan | Retrospective Cohort | Chart Review | Yes | No | 117 | Yes | I-II |
| Kirita | 2012 | International Journal of Oral & Maxillofacial Surgery | Japan | Prospective cohort | Chart Review | No | No | 154 | No | II-IV |
| Kreppel | 2013 | Journal of Cranio-Maxillo-Facial Surgery | Germany | Retrospective Cohort | Chart Review | No | No | 139 | Yes | II-IV |
| Kreppel | 2012 | Oral Oncology | Germany | Retrospective Cohort | Chart Review | Yes | No | 151 | Yes | IV |
| Lyu | 2014 | Journal of Oral and Maxillofacial Surgery | China | Retrospective Cohort | Chart Review | No | No | 22 | No | III-IV |
| Mucke | 2011 | Annals of Surgical Oncology | Germany | Retrospective Cohort | Chart Review | Yes | No | 926 | Yes | I-IV |
| Myers | 2011 | Otolaryngology Head & Neck Surgery | USA | Retrospective Cohort | Chart Review | Yes | No | 70 | Yes | III-IV |
| Sadighi | 2014 | Acta Medica Iranica | Iran | Randomized Controlled Trial | N/A | Yes | No | 24 | No | III-IVa |
| Zhong | 2015 | Oncotarget | China | Randomized Controlled Trial | N/A | Yes | No | 256 | Yes | I-IV |
| Zhong | 2013 | Journal of Clinical Oncology | China | Randomized Controlled Trial | N/A | Yes | No | 256 | Yes | I-IV |
NCDB: National Cancer Database, SEER: Surveillance, Epidemiology, and End Results