PURPOSE

To evaluate the prognostic significance of p16 expression among patients with squamous cell carcinoma of the larynx (LSCC) and hypopharynx (HSCC).

METHODS

The medical records of all patients with locally advanced, non-metastatic LSCC/HSCC were reviewed. p16 (p16) protein expression was evaluated on pathological specimens by immunohistochemistry (IHC), and the Kaplan-Meier method was used to estimate overall survival (OS) and locoregional control (LRC). In select cases, p16 expression was correlated to high-risk and low-risk HPV genotypes using in situ hybridization (ISH).

RESULTS

Thirty-one patients (23 LSCC; 8 HSCC) were identified. Seventeen (54.8%) patients were p16 negative; 14 (45.2%) were p16-positive. The primary treatment modality was radiation therapy for 22 (71.0%) patients and surgery for 9 (29.0%). Nineteen (61.3%) patients were evaluated for high-risk HPV and low-risk HPV genotypes by IHC, of whom 2 (10.5%) patients were positive for high-risk HPV and 1 (5.3%) was positive for low-risk HPV. For high-risk HPV, the positive predictive value (PPV), sensitivity, and specificity of p16 was 20.0%, 100%, and 52.9%. There was no significant difference in the 2-year actuarial rates of OS (91% vs. 64%, p=0.34) or LRC (51% vs. 46%, p=0.69) between the p16-positive and p-16 negative patients.

CONCLUSION

In this small cohort of 31 LSCC and HSCC patients, p16 was not a significant predictive of either LRC or OS. Furthermore, p16 was poorly correlated with HPV genotyping as identified by ISH.