“…The study participants were all diagnosed with head and neck cancer in the laryngeal regions 4,10,12,29,30 , oropharynx 4,12,28 , tongue 29,31,33 , mouth 10,12,[27][28][29][30] , retromolar trigone 29 , epiglottis 29 , amygdala 29 , pharynx 10,12,27,30 , nasophar ynx 33 , thyroid 25,31 , parotid gland 31 , hypopharynx 31,33 , piriform sinus 31 , paranasal sinuses 27 and salivary glands 27 . Five studies did not specify the region 11,14,24,26,32 .…”