p53 protein overexpression and its prognostic significance in adenoid cystic carcinomas of the salivary glands

Purpose: To evaluate p53 protein overexpression in adenoid cystic carcinoma (ACC) of the salivary glands and examine its relation with tumor stage, nodal stage, histological subtype and prognosis of disease. Materials and methods: Fifteen primary ACC cases of the salivary glands were evaluated. Sections from formalin-fixed, paraffin-embedded tissue blocks were stained with anti p53 protein antibody recognising both wild type and mutant forms, by using immunohistochemistry (IHC) with the streptavidine-biotin method. The staining was scored as negative, weak, moderate and strongly positive. The results were correlated with tumor stage, lymph node stage, histologic subtype and prognosis. Results: Eight (53.33%) of the cases were positive, all with weak staining except for a case with metastatic lymph nodes which showed a strong staining for p53 protein. Seventy five percent of T4 cases and 66% of predominantly solid ACC subtype cases were p53 positive. Statistical analysis could not be performed since the number of cases was small. However, the findings suggest p53 protein overexpression in advanced and solid subtype cases. Two of 10 cases with adequate follow up were disease-free after 44 and 60 months, despite the fact that they were p53 positive. Of the 8 cases with tumor recurrence or disease-related death, 3 (37.5%) were p53 positive. Conclusion: These results do not point to a role of p53 protein overexpression as a prognostic factor for ACC of the salivary glands