Abstract: Objective: To investigate the effects of p21, p73 and PTEN expressions in multiple primary cancers of the head and neck. Method: Expressions of p21, p73 and PTEN were determined by the S-P immunohistochemical technique in 42 samples of multiple primary cancer tissues, 42 cases of marched single cancer tissues of the head and neck, and 30 cases of normal epithelial tissues of the head and neck. Results: Positive expression rates of p21, p73 and PTEN in multiple primary cancer tissues and single cancer tissues of the head and neck were 69.05％, 57.14％, 71.43％ and 76.19％, 40.48％, 76.19％, respectively, and those in normal epithelial tissues were 96.66％, 13.33％ and 100.00％. The loss expression rates of p21 and PTEN and the over-expression rates of p73 in multiple primary cancer tissues and single cancer tissues of the head and neck were all significantly higher than those in normal epithelial tissues(P＜0.05), but no significant differences were found between multiple primary cancer tissues and single cancer tissues. Conclusion: The loss of expression of p21 and PTEN and the upregulated expression of p73 may play important roles in tumor genesis of multiple primary cancer and single cancer of the head and neck, but no differences have been found till now between multiple primary cancer and single cancer.

Key words: Multiple primary cancers, Head and neck neoplasms, p21, p73, PTEN, Immunohistochemistry