Langerhans cell number is a strong and independent prognostic factor for head and neck squamous cell carcinomas

Head and neck squamous cell carcinomas (HNSCCs) exhibit great biological heterogeneity and relatively poor prognosis. Tobacco and alcohol consumption is involved in the cause of the majority of these cancers, but over the last several years, Human Papilloma Virus (HPV) infection has increased specifically in oropharyngeal cancers and become an additional risk factor. Here, we evaluated the number of Langerhans cells (LCs) in HNSCC and reporting its prognostic power in comparison to other risk factors.

Our clinical series was composed of 25 tumor-free peritumoral epithelium, 64 low-grade dysplasia, 54 high-grade dysplasia and 125 carcinoma samples. HPV was detected by E6/E7 qPCR and p16 immunohistochemistry. CD1a-positive LCs were counted in intra-tumoral and stromal compartments as well as lymph nodes. MIP-3α was assessed in carcinomas using immunohistochemistry.

Univariate Cox regression analyses demonstrated that high LC number is associated with longer recurrence-free survival in both intra-tumoral and stromal compartments and longer overall survival in stromal compartment. Tobacco and alcohol habits, but not HPV status, are also correlated with poor prognoses in terms of recurrence. Multivariate analyses reported stromal LC number as a strong prognostic factor independent of tobacco, alcohol and HPV status. Moreover, LC number is higher in tumors and invaded lymph nodes than dysplastic lesions but it decreases in HPV-positive cancer patients. Further, LC number correlates with MIP-3α expression.

These findings suggest that LC number is a significant and independent prognostic factor for HNSCC. LC infiltration is increased in cancer lesions but decrease with HPV infection.