Table 1.

Patients’ characteristics from studies included in the meta-analysis.

Study	Institution	Time span	Inclusion criteria	Exclusion criteria	Average age a
					HPV positive	HPV negative
Chan et al.8	University of Toronto, Toronto, Ontario, Canada	April 2009 to June 2015	Newly diagnosed oropharyngeal SCC, age >18 years	Undetermined HPV status	57.7 ± 10.6	62.7 ± 4.8
De Perrot et al.9	Geneva University Hospitals, Geneva, Switzerland	3-year period (published in 2017)	Primary SCC of oropharynx and oral cavity	Lesion not seen on DWI (in situ lesions, T1 stage)	65b	61b
Driessen et al.10	University Medical Center Utrecht, Utrecht, Netherlands	June 2009 to August 2011	T2, T3, and T4 SCC in oral cavity, oropharynx, hypopharynx, or larynx	T1 cancer	57 ± 10	62 ± 9
Nakahira et al.25	Saitama Medical University, Saitama, Japan	April 2007 to August 2012	Biopsy-proven oropharyngeal SCC	DWI not available	62.3b	69.3b
Wong et al.26	Royal Marsden NHS Foundation Trust, Sutton and London, UK	July 2013 to February 2015	Oropharynx, hypopharynx, or larynx SCC, stage III–IVb planned for chemoradiotherapy	—	—	—

^aAverage age (years) ± standard deviation.

^bStandard deviation not provided.

HPV: human papillomavirus; SCC: squamous-cell carcinoma; DWI: diffusion-weighted imaging.