Overexpression of cyclin D1 and interaction between p27Kip1 and tumour thickness predict lymph node metastases occurrence in lower lip squamous cell carcinoma

After univariate analysis, tumour size, histological grading, maximal thickness, perineural invasion and immunoreactivity to cyclin D1 and p27Kip1 proteins proved to be significant factors. Tests of the effect of interaction between p27Kip1 LI and tumour thickness yielded that the impact of tumour thickness on the risk of lymph node metastases was modified by the percentage of p27Kip1 positive cells. Subsequent to models of multivariate analysis, tumour size, positive cyclin D1 protein expression, maximal thickness (>5 mm), p27Kip1 LI (%) and the interaction term between p27Kip1 LI and tumour thickness retained strong independent predictive values for lymph node metastases. We suggest that immunohistochemistry for cyclin D1 and p27Kip1 may prove to be valuable ancillary tests for identifying LLSSC with metastatic potential.