Prognostic implications of sialosyl-Tn antigen expression in sinonasal intestinal-type adenocarcinoma

The expression of the mucin antigen sialosyl-Tn (S-Tn) was evaluated immunohistochemically in a series of 30 intestinal type adenocarcinomas of the nasal cavities and paranasal sinuses to assess the relationship between the histological features of the lesions and their clinical behaviour. In grades 1 and 2 adenocarcinomas, the staining localised at the apical pole or within the cytoplasm of neoplastic cells, and in the content of glandular structures. Grade 3 adenocarcinomas had a very scanty expression of the antigen. Mucinous adenocarcinomas showed an intense immunoreaction within the cell cytoplasm and in the extracellular mucous pools. Conversely, non-neoplastic sinonasal mucosa had a very focal distribution of the antigen. Immunostaining was scored according to the percentage of low power microscopic fields showing positivity. Twenty-one adenocarcinomas (70%) were considered positive. No significant relationship was found between S-Tn positivity and the histological degree of differentiation of the lesion. The 5-year survival rate and disease-free interval of patients with S-Tn positive adenocarcinomas were significantly lower than those with negative adenocarcinomas (17.8% versus 72%, P = 0.0001; 16.6% versus 40%, P = 0.0001, respectively). These results indicate that S-Tn immunostaining appears to be a significant prognostic factor in patients with sinonasal intestinal type adenocarcinoma.