p16 Positive Squamous Cell Carcinomas of the Larynx Are Predominantly Located in the Supraglottis Compared to Glottic and Subglottic Locations.
Sean M Kirby, Marino Leon, Hans Iwenofu. The Ohio State University, Columbus
Background: The significance of human papillomavirus (HPV) in squamous cell carcinomas (SCC) of the head and neck is well established, particularly in oropharyngeal cancers. Expression of p16 is strongly associated with HPV infection and its utility as a surrogate marker has been validated in previous studies. There is precedent literature on HPV associated laryngeal carcinomas but its anatomic distribution within the larynx has not been previously studied. Herein, using p16 immunohistochemistry, we examined expression in laryngeal SCC relative to supraglottic, glottic, and subglottic locations.
Design: A computerized search yielded 150 patients with squamous cell carcinoma of the larynx at the Ohio State University Medical Center. Cases which could not be identified as solely supraglottic, glottic, or subglottic were eliminated from the study. The remaining cases (n=101) were sorted into supraglottic (n=46), glottic (n=52), and subglottic (n=3) groups. Representative sections of tumor were used to construct a tissue microarray (TMA), including two 1.5 mm cores of tissue per case. The TMAs were stained for p16 using routine methods in a DAKO automated stainer. The results were then evaluated semiquantitatively for intensity (0-3+) and percent of tumor cells stained. Staining of <5% was considered negative.
Results: Expression of p16 was found in 18% of all laryngeal SCCs. Supraglottic tumors showed a higher rate of 30% (14/46) with 8 cases staining >75% of the tumor cells with 2-3+ intensity. Glottic tumors had a rate of 8% (4/52) with more focal distribution. 1 of 3 (33%) subglottic tumors was positive with staining of <10% of cells. The results are summarized below. The difference in p16 expression for supraglottic and glottic groups were statistically different (p<0.05).