Objective: The P21waf is a tumor-suppressor protein encoded by CDKN1A gene. In this study, we evaluated P21waf expression and CDKN1A exon 2 mutation and their relationships with clinicopathological parameters and cancer development in salivary adenoid cystic carcinoma (ACC).

Patients and Methods: Forty paraffin blocks from patients with salivary ACC were collected. Immunohistochemical staining was performed using P21 antibody. Genomic DNAs were extracted from the deparaffinized sections of the embedded tissue. Exon 2 of CDKN1A gene was amplified by PCR and the PCR products were sequenced. Spearman’s correlation coefficient, Fisher’s exact test, and Kruskal-Wallis test were used for data analysis.

Results: A significant inverse correlation was observed between P21 expression and histologic grade (p=0.033, r=-0.338). The correlation of tumor size with recurrence (p=0.048) and tumor stage (p=0.046) was also evidenced. No mutation was detected in the exon 2 of CDKN1A gene.

Conclusions: Regarding the association of P21 expression and histologic grade as a major prognostic indicator of ACC, P21 may be a useful prognostic indicator in ACC. On the other hand, CDKN1A exon 2 mutation seems inapplicable as a risk factor for ACC development.