In contrast, no association was observed between either MMP3-1171 5A>6A or MMP9-1562 C>T polymorphism and HNC risk in overall comparison; however, in subgroup analyses based on ethnicity and tumor site, significant associations were found between the MMP3-1171 5A>6A polymorphism and HNC risk in Europeans and pharyngeal/laryngeal cancer under two genetic contrasts. This evidence concerns the gene MMP9 and neoplasm.