Abstract
BackgroundProgrammed cell death ligand 1 (PD-L1) expression was reported to be correlated with poor prognosis in various cancers. However, the relationship between PD-L1 expression and the survival of patients with head and neck cancer (HNC) remains inconclusive. In the present study, we aimed to clarify the prognostic value of PD-L1 in HNC patients using meta-analysis techniques.MethodsA comprehensive database searching was conducted in the PubMed, EMBASE, Web of Science and Cochrane Library from inception to August 2016. Studies meeting the inclusion criteria were included. The methodological quality of included studies was assessed by the Newcastle-Ottawa quality assessment scale. Hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs) were pooled by STATA 11.0 for the outcome of overall survival (OS) and disease-free survival (DFS).ResultsA total of 17 studies with 2,869 HNC patients were included in the meta-analysis. The results of meta-analysis showed that there was no significant correlation between PD-L1 expression and OS (HR, 1.23; 95% CI, 0.99–1.53; P = 0.065) or DFS (HR, 1.42; 95% CI, 1.00–2.03; P = 0.052) of HNC patients. However, the subgroup analysis suggested that positive expression of PD-L1 was associated with poor OS (HR, 1.38; 95% CI, 1.12, 1.70; P = 0.003) and DFS (HR, 1.99; 95% CI, 1.59, 2.48; P = 0.001) in HNC patients from Asian countries/regions. The subgroup analysis also showed that the correlations between PD-L1 and prognosis are variant among different subtypes of HNC. When performing sensitive analyses, we found that the results of meta-analyses were not robust.ConclusionThe meta-analysis indicated that positive expression of PD-L1 could serve as a good predictor for poor prognosis of Asian patients with HNC. However, the findings still need to be confirmed by large-scale, prospective studies.
Highlights
Head and neck cancer (HNC) is a group of cancers that starts within the oral cavity, nasal cavity, larynx, pharynx, or salivary glands [1]
The results of meta-analysis showed that there was no significant correlation between programmed cell death ligand 1 (PD-L1) expression and overall survival (OS) (HR, 1.23; 95% confidence intervals (CIs), 0.99–1.53; P = 0.065) or disease-free survival (DFS) (HR, 1.42; 95% CI, 1.00– 2.03; P = 0.052) of HNC patients
Four studies included patients diagnosed with head and neck squamous cell carcinoma (HNSCC) [5, 22,23,24] while the remaining studies included patients diagnosed with the subtypes of HNC: six studies included patients with oral squamous cell carcinoma (OSCC) [19, 20, 29, 33, 35, 36], three studies included patients with nasopharyngeal carcinoma (NPC) [21, 30, 32], two studies included patients with oropharyngeal squamous cell carcinoma (OPSCC) [31, 37], one study included patients with laryngeal squamous cell carcinoma (LSCC) [38], and one study included patients with salivary gland carcinoma (SGC) [34]
Summary
Head and neck cancer (HNC) is a group of cancers that starts within the oral cavity, nasal cavity, larynx, pharynx, or salivary glands [1]. Programmed cell death ligand 1 (PD-L1) was demonstrated to be involved in the immune escape mechanism of cancer cells [8, 9]. PD-L1 is limitedly expressed and interacts with its receptor, programmed cell death 1 (PD-1), to protect healthy cells from excessive inflammatory or autoimmune responses [11, 12]. Blockade of PD-L1 with monoclonal antibody has shown promising results for increasing survival rates of patients with melanoma or renal cell cancer [17, 18]. Programmed cell death ligand 1 (PD-L1) expression was reported to be correlated with poor prognosis in various cancers. The relationship between PD-L1 expression and the survival of patients with head and neck cancer (HNC) remains inconclusive. We aimed to clarify the prognostic value of PD-L1 in HNC patients using meta-analysis techniques
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