Purpose: The purpose of this study is to determine whether CK2 expression may be a biomarker for clinical outcomes in advanced oropharyngeal squamous cell carcinoma.
Background: Elevated protein kinase CK2 protein and activity has correlated with poor clinical outcome in patients with various cancers. CK2 is a serine/threonine kinase that has a broad range of intracellular roles that include regulation of apoptosis and DNA repair. However, the prognostic or predictive value of CK2 has not been studied in HPV-related oropharyngeal squamous cell carcinoma (OPSCC).
Methods: A retrospective cohort study of patients diagnosed with OPSCC from 2005-2015 in the Minneapolis Veterans Affairs Healthcare System was performed. Patient demographic, treatment, and clinical outcome data were collected. Archived tumor tissue blocks were stained for p16 (surrogate for HPV-positivity) and CK2α via immunohistochemistry (IHC). The CK2α IHC stain was scored by two staff pathologists with an ordinal scale of 1 (weak) to 3 (strong).
Data Analysis: X2 test of independence, with the 0.01 level considered significant for observed differences
Results: A total of 116 patients were identified that met inclusion criteria. IHC staining for p16 was positive in 80/116 (69%) patients and negative in 36/116 (31%) patients. Overall survival (OS) and progression-free survival (PFS) at 4 years postdiagnosis for p16-positive tumors (p16+) was 71% and 64%, respectively, while the OS and PFS at 4 years for p16-negative tumors was 36% and 32%, respectively. For CK2 IHC scores 1, 2, and 3, respectively, the OS at 4 years was 31%, 75%, and 65%, respectively, while the PFS for scores 1, 2, and 3 at four years was 32%, 65%, and 53%, respectively. In the CK2 IHC score groups, 1, 2, and 3, respectively, p16 positivity vs. negativity was 26% vs. 74%, 79% vs. 21%, and 89% vs. 11%, respectively.
Implications: High CK2 abundance is associated with higher PFS and OS at 4 years in patients with p16+ OPSCC. Further study is needed better define the relationship between p16 expression and CK2 expression in OPSCC.
