Argyrophilic nuclear organizer region and p73 expression in head and neck squamous cell carcinomas: Teammates or adversaries?

CONTEXT: Head and neck squamous cell carcinoma (HNSCC) consists of squamous cell carcinomas (SCCs) arising in the upper aerodigestive tract and accounts for 5% of cancers worldwide. In Malaysia, cancers of the nasopharynx, larynx, tongue and oral cavity are among the top twenty most common cancers in men. Argyrophilic nuclear organizer regions (AgNORs) are increased from normal mucosa to premalignant lesions to malignant lesions and have been associated with tumor grade and prognosis of patients. Although p73 is not mutated in human cancers, high levels of p73 expression have been associated with tumor differentiation status and patient prognosis.

AIMS: To investigate the correlation between AgNORs and p73 immunoexpression.

SETTINGS AND DESIGN: Fifty-two formalin-fixed, paraffin-embedded HNSCC cases and ten controls were collected from the Hospital.

SUBJECTS AND METHODS: Tissue blocks were sectioned, dewaxed and rehydrated before silver nitrate staining to determine the AgNOR count and immunohistochemical staining to determine the p73 expression. Adopting the scoring system used by Chen et al. for p73 staining, the proportion of positively stained cells in the whole epithelial layer was determined. Staining was considered positive if >10% of epithelial cells were stained.

STATISTICAL ANALYSIS USED: Spearman's correlation coefficient was calculated using SPSS 18 software to determine the relationship between the p73 score against tumor differentiation, mean AgNOR counts and tumor grade and between the mean AgNOR count and p73 score.

RESULTS: Positive results were found in the immunoexpression of p73. Positive results were seen with the staining of AgNOR; however, in comparison with the entire sample size, a significant correlation between mean AgNOR count and p73 immunohistochemical expression was not obtained.

CONCLUSIONS: AgNOR count showed a linear and decreasing trend as the p73 score increases. This correlation was statistically insignificant.