In oral squamous cell carcinoma, low PER2 expression was connected to poor prognosis, tumor grade progression, and lymph node metastasis (Xiong et al., 2018), whereas in lung cancer, increased PER2 expression was associated with less malignant differentiation and fewer lymph node metastases (Xiang et al., 2018). Here, PER2 is linked to oral cavity squamous cell carcinoma.