Results
Description of the studies
In total, 1540 articles were initially identified and five were finally
selected according to the exclusion criteria, with a total of 2005
patients The specific screening process is shown in Figure 1. The five
articles included four phase III RCT clinical trials and one phase II
RCT clinical trial. Treatment with PD-1/PD-L1 inhibitors was one of the
intervention programmes, and this was compared with other treatment
methods. Overall response rate (ORR), overall survival (OS), and
progression-free survival (PFS) were the end points in each study. The
median follow-up time ranged from 5.2 to 17 months. Specific information
on each study is shown in Table 1 and the results of methodological
quality evaluation for each study are shown in Table 2.
[Figure 1 near here]
Outcome results of meta-analysis
Overall response rate (ORR): All five of the articles reported the ORR
of the patients in each group. Through software analysis (Figure 2),
there was heterogeneity between the studies (I2 = 87%), so using the
random effects model, the results showed that there was no statistically
significant difference between the group treated with PD-1/PD-L1 and the
group with other treatments (P = 0.35).
[Figure 2 near here]
Overall survival (OS): Four of the five articles reported the OS in each
experimental group. Through software analysis (Fig. 3), there was no
heterogeneity (I2 = 0%), so the fixed effects model was used. The
results showed that treatment with PD-1/PD-L1 inhibitors alone could
reduce the risk of death in patients with recurrent/metastatic HNSCC,
and the difference between patients treated with PD-1/PD-L1 and the
group with other treatments was statistically significant (P = 0.004).
[Figure 3 near here]
Progression-free survival (PFS): Four of the five articles reported the
PFS of patients in each group. Through software analysis (Figure 4),
there was no heterogeneity (I2 = 0%), so the fixed effects model was
used. The results showed that there was no statistically significant
difference in PFS between the group treated with PD-1/PD-L1 and the
group with other treatments (P = 0.47).
[Figure 4 near here]
Adverse events
The five articles included in the study reported the adverse events of
diarrhoea, asthenia, rash, fatigue, anaemia and nausea after treatment.
Meta-analysis showed that there was no significant difference in
diarrhoea, asthenia, rash or fatigue between the PD-1/PD-L1 inhibitor
treatment group and the other treatment group, but PD-1/PD-L1 inhibitor
treatment significantly reduced the risk of anaemia (P <
0.0001) and nausea (P < 0.0001), as shown in Table 3.
Publication bias analysis
A funnel chart test was carried out for OS, PFS, ORR and adverse
reaction results to judge the effect of possible publication bias.
However, due to the inclusion of less than 10 documents, it was
impossible to use a forest map to judge publication bias. In order to
reduce the effects of publication bias, we searched the unpublished
clinical trial registry data. We use search terms Head and Neck Squamous
Cell Carcinoma, and also searched for Squamous cell carcinoma of head
and neck, Squamous cell carcinoma of the head and neck, head and neck
cancer, head and neck neoplasms or HNSCC and PD-1/PD-L1 inhibitors or
Pembrolizumab or Keytruda or Nivolumab or Opdivo or Durvalumab or
MEDI4736 or Atezolizumab or checkpoint inhibitors. We found 217 studies
but after removal of duplicates and consideration of inclusion criteria,
we had to remove them all.