A decreased level of SFRP1 protein was observed in the head and neck squamous cell carcinoma [45], cutaneous squamous cell carcinoma [25], and gastric cancer [30], while increased protein concentration was reported in basaloid oesophageal squamous cell carcinoma samples [36] and breast cancer tissue specimens [44]. Here, SFRP1 is linked to head and neck squamous cell carcinoma.