Fig. 1Immunohistochemically, c-Met is positive in the cytoplasm or membrane of head and neck carcinoma with the variable intensity scored as 0 (A), 1 (B), 2 (C), and 3 (D).
Fig. 2Expression of c-Met is different along the tumor location of the head and neck and in the grade of differentiation. In the hypopharynx, oral cavity, and oropharynx, c-Met is highly expressed, whereas in the larynx and nasopharynx, the expression is quite low in less than a half of the total cases (A). More differentiated tumors also show a more frequent c-Met positivity (B). Hypophx, hypopharynx; Oral, oral cavity; Orophx, oropharynx; Nasphx, nasopharynx; WD, well differentiated; MD, moderately differentiated; PD, poorly differentiated; UD, undifferentiated carcinoma.
Fig. 3Fluorescence in situ hybridization study with a c-Met gene probe (red) on chromosome 7q31 shows a normal gene copy number in most of the cases (A), except for one case showing clustered red signals indicating gene amplification (B) in head and neck carcinoma.
Fig. 4High expression of c-Met in head and neck carcinoma does not affect the patients' outcomes measured by overall survival (A) and progression free survival (B).
Table 1Association between the expression of c-Met and clinicopathologic variables