TGF-alpha immunoreactivity in laryngeal carcinoma: Lack of prognostic value and correlation to EGF-receptor expression

Background: Transforming growth factor alpha (TGF-α) is a polypeptide that is structurally similar to epidermal growth factor (EGF) that binds to the epidermal growth factor receptor (EGFR) and has been implicated in the development of several types of human tumours. Methods: The expression of TGF-α is examined in laryngeal squamous cell carcinomas (SCC) (n = 24) and non-neoplastic polyps (n = 7) using streptavidin-biotin immunohistochemistry and a monoclonal antibody to the TGF-α protein. These cases had been previously characterized for EGFR immunoreactivity. The carcinomas were classified as well differentiated (n = 2), moderately differentiated (n = 16) and poorly differentiated (n = 6). Tissues from metastatic tumour deposits in lymph nodes (n = 5) were also studied. Results: TGF-α overexpression was defined as intense immunoreactivity in more than two-thirds of tumour cells immunostained for TGF-α and was present in the majority of the SCC cases (n = 15; 63%) and metastatic tumour deposits (n = 4; 80%). In contrast, although some of the cord polyps showed weak (n = 2) to moderate (n = 5) immunostaining, none had evidence of strong TGF-α immunoreactivity. The differences in TGF-α immunoreactivity were significant between primary laryngeal SCC and vocal cord polyps (P = 0.013; χ test with continuity correction), and between metastatic laryngeal SCC and vocal cord polyps (P = 0.023; χ² test with continuity correction). There was no significant difference in TGF-α expression between the different grades of carcinomas (P = 0.92, χ² test) or between non-metastatic and metastatic carcinomas (P = 0.82; χ² test with continuity correction). No significant correlation was found between TGF-α expression and patient survival or tumour recurrence (r = 0.077, r² = 0.006, P = 0.75; simple regression analysis), or between TGF- α expression and EGFR immunoreactivity (r = 0.325, r² = 0.106, P = 0.0851). Conclusions: In conclusion, increased TGF-α immunoreactivity is present in most cases of laryngeal SCC with specific relationship to tumour grade, suggesting that in may be important in the development of laryngeal carcinomas but not in its progression. NO significant correlation was found between TGF-α and EGFR expression in laryngeal tumours and TGF-α immunoreactivity is of no prognostic value.