Adenoid cystic carcinoma of the salivary gland: a clinicopathological study of 49 cases and of metallothionein expression with regard to tumour behaviour

AimsAdenoid cystic carcinoma (AdCC) of the salivary glands shows heterogeneous behaviour, with metastasis as a key indicator of poor prognosis. Metallothionein (MT) expression has been associated with poor prognosis of diverse neoplasms. We evaluated prognostic factors for AdCC and the role played by MT, focusing on metastatic behaviour. Methods and resultsWe reviewed the files of the Brazilian National Institute of Cancer between 1997 and 2004, obtaining 49 cases. Fourteen tumours had metastasized during follow-up. Among these, we identified cases presenting with metastasis at patient admission as showing the poorest survival rates. MT immunostaining of the tumours was performed (using the E9 antibody), and evaluated for the parameters of proportion, intensity and distribution in tumour cells. Extent and intensity of staining, and Quickscore (a combined measure of extent and intensity), were higher in metastatic than non-metastatic tumours (for Quickscore, P=0.044), with highest values found for cases of early metastasis. Most cases showing weak staining, and all with a predominantly cytoplasm-restricted staining pattern, were non-metastatic. Metastatic tumours of solid type received higher scores than solid non-metastatic (Intensity, P=0.0239; Quickscore, P=0.0481). ConclusionsOur results demonstrated metastasis to be the most significant indicator of poor prognosis and deterioration for AdCC. Consistent patterns of MT expression were observed to correlate with metastatic behaviour, indicating that MT may potentially serve as a prognostic marker for AdCC.