METHODS
A total of 164 patients diagnosed with papillary thyroid cancer were included in our study. Immunoscore
was evaluated by immunohistochemistry according to CD3+ and CD8+ T lymphocyte density at the
tumor center and at the tumor margin. Immunoscore values were calculated. PD-L1 was evaluated by
immunohistochemistry according to its density at the tumor center and at the tumor margin. The relationships
between the parameters studied were evaluated statistically.
RESULTS
The presence of PD-L1 at the tumor centers in CD8+ T lymphocytes height was also significantly higher
(p<0.001). There was no significant relationship between PD-L1 expression at the tumor center and LN
metastasis and tumor size ( p>0.999 and p=0.226, respectively). In the presence of PD-L1 expression at
the tumor margin, LN metastasis (p<0.001) and tumor size (p=0.029) were higher. PD-L1 expression at
the tumor margin was significantly associated with overall survival (p<0.001).
CONCLUSION
In particular, immunoscore value can be a good prognostic marker and its significant association with
conditions associated with poor prognosis, such as PD-L1 expression, suggests that it may be a parameter
that can be used and guided in stage scoring.
Keywords: Immunoscore; papillary thyroid cancer; programmed death-ligand 1; prognosis
Contrary to the infiltration of cells responsible for
chronic inflammation, it has been reported that the
presence of a high number of T lymphocyte in cancers
such as colon cancer, melanoma, lung cancer, pancreatic
cancer, hepatocellular carcinoma, breast cancer is an
indicator of good prognosis.[
The immune checkpoint is of great importance in
the recognition of CTLs by the tumor. Programmed
death-ligand 1 (PD-L1) is expressed by B and T cells,
monocytes, macrophages, and dendritic cells and
plays an important role in the regulation of immune
responses.[
The relationship between IS and PD-L1 expression
in PTC, clinical features and prognosis of PTC remain
unclear. In this study, the relationship between IS and
PD-L1 expression in PTC, clinical features, overall survival
and prognostic value was investigated.
PTC: Papillary thyroid carcinoma.
Statistical Analysis
All statistical analyses were performed using R version
3.6.0 (The R Foundation for Statistical Computing,
Vienna, Austria; https://www.r-project.org). Numerical
variables such as age were expressed as mean ±
standard deviation, and categorical variables were expressed
as numbers (n) and percent (%). Yates continuity
correction Chi-square and Fisher"s exact test were
performed to determine whether there was a statistically
significant relationship between CD3+ and CD8+
T lymphocytes, PD-L1 expression, and tumor size and
lymph node (LN) involvement. In addition, significant
relationships with phi (ϕ) coefficients as effect size and odds ratio were expressed with 95% confidence interval
over 2×2 cross tables. OS was defined as the time from
diagnosis to date of death from any cause. The survival
curves of CD3+, CD8+, and PD-L1 were estimated using
the Kaplan?Meier method and Log-rank tests were
used to compare the difference. Bipolar p<0.05 was
considered statistically significant.
LN involvement was observed in 2 (9.0%) of 22 patients
with PD-L1 positive at the tumor center and 14
(10.1%) of 138 patients who were negative. LN involvement
was lower in patients with PD-L1 expression at
the tumor center. The difference between these two
ratios was not statistically significant (p>0.999). Furthermore,
there was no statistically significant correlation
between PD-L1 at the tumor center and tumor size
(p=0.226). LN involvement was observed in 11 (100%)
of 11 patients with positive PD-L1 tumor margin. The
difference between these two ratios was statistically
significant (p<0.001) (Table
Of the 164 PTC patients, 10 (7.2%) died during
the follow-up period. Median follow- up was 1065
days (range: 78?3890 days). In Kaplan?Meier analysis,
CD3+ and CD8+ T lymphocyte levels and PD-L1
expression at the tumor center did not show a significant
association with OS (Log-rank ?2=0.921, p=0.337;
Log-rank χ2=2.451, p=0.117; and Log-rank χ2=0.001,
p=0.987; respectively) (Fig.
PTC: Papillary thyroid carcinoma
Most studies have shown that high density of CD3+
and CD8+ T lymphocytes are associated with longer
disease-free survival (DFS) and/or improved OS.[
In some studies, they did not find a significant relationship
between CD8+ T lymphocytes infiltration and
tumor size.[
However, besides the relationship between PD-L1
expression and PTC, the clinical features and prognosis
of PTC still remain unclear. In our study, the rate
of positive immunostaining for PD-L1 expression at
the tumor center was approximately six-fold higher in
cases with elevated CD8+ T lymphocytes (p<0.001).
The high infiltration rate of CD8+ T lymphocytes was
approximately three-fold higher in subjects with high
CD3+ T lymphocytes (p<0.001). These ratios show
that CD8+ T lymphocytes are more valuable in determining
the IS. It also supports that the IS is a strong
prognostic marker. The IS can add additional power
to the TNM classification, prognosis, and follow-up
of patients. This information supports that CD3+ and
CD8+ T lymphocytes are associated with progression
and survival of thyroid cancer patients.
In our study, we examined whether there is a statistically
significant relationship between CD3+ and CD8+
T lymphocytes, PD-L1 expression, and LN involvement.
LN involvement was observed in 2 (9.5%) of 22 positive
patients and 14 (10.1%) of 138 negative patients in the
PD-L1 at the tumor center. The difference between these
two ratios was not statistically significant (p>0.999). LN
involvement was observed in 11 (100%) of 11 patients
who were positive at the PD-L1 expression at the tumor
margin. The difference between these two ratios is statistically
significant (p<0.001). LN involvement was observed
in 11 (14.9%) of 74 patients with high CD3+ T
lymphocyte levels and 5 (5.8%) of 86 patients with low
CD3+ T lymphocyte levels. The difference between these
two ratios was not statistically significant (p=0.101). LN
involvement was observed in 9 (13.2%) of 68 patients with
high CD8+ T lymphocyte levels and 7 (7.6%) of 92 patients with low CD8+ T lymphocyte levels. The difference
between these two ratios was not statistically significant
(p=0.365). In our study, there was no statistically significant
relationship between CD3+ and CD8+ T lymphocyte
infiltrations, PD-L1 expression, and LN involvement.
This shows us that LN metastasis develops independently
of these parameters in early stage PTC. One study found
that patients who were PD-L1 expression negative at the
tumor center had a significantly longer survival than patients
who were positive for PD-L1 at the tumor margin.
[40] In our study, we found that LN involvement was less
in patients with PD-L1 expression tumor center and LN
involvement was higher in patients with PD-L1 expression
at the tumor margin. This suggests that it is associated
with shortened survival and shortened DFS. This
information suggests that PD-L1 may be a biomarker for
LN involvement in cases with PD-L1 expression at the
tumor margin. As a biomarker, it can be used to monitor
the survival and prognosis of cases.
Immune checkpoint inhibitors have made major
contributions to the treatment of malignancies.
[
Peer-review: Externally peer-reviewed.
Conflict of Interest: All authors declared no conflict of interest.
Ethics Committee Approval: The study was approved by the Selçuk University Faculty of Medicine Local Ethics Committee (no: 2022/190, date: 12/04/2022).
Financial Support: None declared.
Authorship contributions: Concept - C.U., S.B., M.K.K., M.B.; Design - C.U., S.B., M.K.K., M.B.; Supervision - C.U., S.B., M.K.K., M.B.; Funding - C.U., S.B., M.K.K., M.B.; Materials - C.U., S.B., M.K.K., M.B.; Data collection and/or processing - C.U., S.B., M.K.K., M.B.; Data analysis and/or interpretation - C.U., S.B., M.K.K., M.B.; Literature search ? C.U., S.B., M.K.K., M.B.; Writing - C.U., S.B., M.K.K., M.B.; Critical review - C.U., S.B., M.K.K., M.B.