Study selection
The flow chart of study selection process was depicted in Figure 1. A total of 251 studies were identified from online databases, including PubMed, Cochrane Library, Web of Science and Embase. Based on screening of titles and abstracts, 54 studies were selected for further investigation according to following criteria: repetitive articles, not a human study, not original articles, no clinical parameters, unrelated to TSP-1, unrelated to malignant neoplasms and unrelated to prognosis or survival. Of these 54 studies, 30 were excluded due to insufficient survival data and overlapping data. Ultimately, 24 articles were included for further analysis.
Study characteristics
The major characteristics of the eligible data were summarized in Table 1. We collected basic data on 24 articles published between 2000 and 2019. The meta-analysis included 2379 participants from different regions of the United States, France, Japan, China, India, Greece, the United Kingdom and Norway, including tumors such as breast cancer, liver cancer, ovarian cancer, esophagus cancer, lung cancer, gastric cancer, colon cancer, skin cancer, cervical cancer, oral cancer and bladder cancer.
Table.1 Main characteristics of studies included in the meta-analysis
First author, Publication year
|
Case nationality
|
Male(%)
|
Dominant ethnicity
|
Main pathological type
|
Disease type
|
Detected sample
|
Outcome measures
|
Source of HR
|
Maximum months of follow-up
|
Assay method
|
|
|
Nakamura et al, 2019
|
Japan
|
0.79
|
Asian
|
Urothelial carcinoma
|
Bladder cancer
|
Tissue
|
PFS
|
Reported
|
95
|
IHC
|
|
Tzeng et al, 2016
|
China
|
N/A
|
Asian
|
Squamous cell carcinoma
|
Esophagus cancer
|
Tissue
|
PFS
|
SC
|
228
|
IHC
|
|
Rouanne et al, 2016
|
France
|
0.67
|
Caucasian
|
Adenocarcinoma
|
Lung cancer
|
Serum
|
OS/DFS
|
Reported
|
34
|
ELISA
|
|
Teraoku et al, 2016
|
Japan
|
0.35
|
Asian
|
Adenocarcinoma
|
Colon cancer
|
Tissue
|
OS/DFS
|
SC
|
168
|
IHC
|
|
Campone et al, 2015
|
France
|
N/A
|
Caucasian
|
Adenocarcinoma
|
Breast cancer
|
Tissue
|
OS
|
SC
|
279
|
IHC
|
|
Eto et al, 2015
|
Japan
|
0.8
|
Asian
|
Adenocarcinoma
|
Gastric cancer
|
Tissue
|
OS
|
SC
|
60
|
IHC
|
|
Yao et al, 2014
|
China
|
0.68
|
Asian
|
Non-Small Cell Lung Cancer
|
Lung cancer
|
Tissue
|
OS/DFS
|
Reported
|
60
|
ELISA
|
|
Sharma et al, 2013
|
India
|
92.5
|
Asian
|
Hepatocellular Carcinoma
|
Liver cancer
|
Tissue
|
OS
|
Reported
|
33
|
PCR
|
|
Pectasides et al, 2012
|
Greece
|
0
|
Caucasian
|
Adenocarcinoma
|
Breast cancer
|
Tissue
|
OS/PFS
|
Reported
|
45
|
PCR
|
|
Nakao et al, 2011
|
Japan
|
0.8
|
Asian
|
Adenocarcinoma
|
Gastric cancer
|
Tissue
|
OS
|
SC
|
50
|
IHC
|
|
Zhou et al, 2009
|
China
|
0.73
|
Asian
|
Squamous cell carcinoma
|
esophagus cancer
|
Tissue
|
OS
|
Reported
|
50
|
IHC
|
|
Randall et al, 2009
|
USA
|
N/A
|
Caucasian
|
Squamous cell carcinoma
|
Cervical cancer
|
Tissue
|
OS/PFS
|
Reported
|
184.8
|
IHC
|
|
Yang et al, 2009
|
China
|
0.51
|
Asian
|
mucoepidermoid carcinoma
|
Oral cancer
|
Tissue
|
DFS
|
SC
|
60
|
IHC
|
|
Secord et al, 2007
|
USA
|
0
|
Caucasian
|
Epithelial cancer
|
Ovarian cancer
|
Tissue
|
OS/PFS
|
Reported
|
110
|
Immunoblot analysis
|
|
Wada et al, 2006
|
Japan
|
0.75
|
Asian
|
Hepatocellular Carcinoma
|
Liver cancer
|
Tissue
|
DFS
|
SC
|
60
|
IHC
|
|
Sutton et al, 2005
|
UK
|
0.67
|
Caucasian
|
Adenocarcinoma
|
Colon cancer
|
Tissue
|
OS
|
Reported
|
60
|
Dextran polymer conjugate wwo-step visualization system
|
|
Fontana et al, 2005
|
France
|
N/A
|
Caucasian
|
Adenocarcinoma
|
Breast cancer
|
Tissue
|
PFS
|
SC
|
160
|
IHC
|
|
Poon et al, 2004
|
China
|
0.82
|
Asian
|
Hepatocellular Carcinoma
|
Liver cancer
|
Tissue
|
OS
|
SC
|
38
|
IHC
|
|
Aishima et al, 2002
|
Japan
|
N/A
|
Asian
|
Intrahepatic Cholangiocarcinoma
|
Liver cancer
|
Tissue
|
OS
|
SC
|
120
|
IHC
|
|
Maeda et al, 2001
|
Japan
|
0.63
|
Asian
|
Adenocarcinoma
|
Colon cancer
|
Tissue
|
DFS
|
Reported
|
60
|
IHC
|
|
Straume et al, 2001
|
Norway
|
N/A
|
Caucasian
|
Melanomas
|
Skin cancer
|
Tissue
|
OS
|
SC
|
210
|
IHC
|
|
Kodama et al, 2001
|
Japan
|
N/A
|
Asian
|
Squamous cell carcinoma
|
Cervical cancer
|
Tissue
|
DFS
|
Reported
|
59
|
PCR
|
|
You et al, 2000
|
China
|
0.57
|
Asian
|
Squamous cell carcinoma
|
Lung cancer
|
Tissue
|
OS
|
SC
|
120
|
IHC
|
|
Yao et al, 2000
|
Japan
|
N/A
|
Asian
|
Squamous cell carcinoma
|
Oral cancer
|
Tissue
|
OS
|
SC
|
60
|
IHC
|
|
OS, overall survival; DFS, disease-free survival; PFS, progression-free survival; SC: survival curve; IHC, Immunohistochemistry; PCR, polymerase chain reaction; ELISA, enzyme linked immunosorbent assay; N/A, not available.
The expression of TSP-1 was measured by Immunohistochemical staining (IHC) in the most of studies. Besides, Quantitative real-time polymerase chain reaction (qRT-PCR) assay and enzyme linked immunosorbent assay (ELISA) was applied to detect TSP-1 in 3 and 2 studies, respectively, and immunoblot analysis and a standard Dextran Polymer Conjugate Two-step Visualization system Envision was applied in 1 study each. The data of HR and 95% CI was extracted from survival curves or literature reports. In all these studies, 17 studies researched OS [17, 22-37], 7 studies investigated DFS/RFS [22, 23, 26, 38-41] and 6 studies focused on progression-free survival (PFS)/ metastasis-free survival (MFS) [28, 31, 32, 42-44] (Table 2).
Table.2 HRs and 95% CIs of cancer prognosis and progression associated with TSP-1 expression in included studies
First author, Publication year
|
Cut-off value
|
Number of cases
|
|
OS
|
|
DFS/RFS
|
|
PFS/MFS
|
High expression
|
low expression
|
Total
|
|
HR (95% CI)
|
P Value
|
|
HR (95% CI)
|
P Value
|
|
HR (95% CI)
|
P Value
|
Nakamura et al, 2019
|
10% of the cells were positive
|
86
|
120
|
206
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
|
1.11 (0.56-2.19)
|
0.774
|
Tzeng et al, 2016
|
value =40
|
76
|
107
|
183
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
|
0.61 (0.38-0.99)
|
<0.001
|
Rouanne et al, 2016
|
Median
|
N/A
|
N/A
|
171
|
|
0.15 (0.03–0.89)
|
0.04
|
|
0.39 (0.10–1.45)
|
0.23
|
|
N/A
|
N/A
|
Teraoku et al, 2016
|
score=3
|
35
|
59
|
94
|
|
2.61 (1.00-8.16)
|
<0.01
|
|
0.63 (0.38-1.06)
|
0.06
|
|
N/A
|
N/A
|
Campone et al, 2015
|
positive
|
19
|
14
|
33
|
|
0.86 (0.08-8.85)
|
0.0364
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Eto et al, 2015
|
10% of the cells were positive
|
17
|
48
|
65
|
|
0.53 (0.24-1.18)
|
<0.05
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Yao et al, 2014
|
Median
|
N/A
|
N/A
|
68
|
|
1.52 (0.91–3.14)
|
0.088
|
|
1.62 (0.91–3.76)
|
0.112
|
|
N/A
|
N/A
|
Sharma et al, 2013
|
Median
|
N/A
|
N/A
|
67
|
|
0.982 (0.541-1.784)
|
0.953
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Pectasides et al, 2012
|
Median
|
60
|
60
|
120
|
|
1.84 (1.11-3.05)
|
0.018
|
|
N/A
|
N/A
|
|
1.73 (1.11-2.69)
|
0.016
|
Nakao et al, 2011
|
30% of the cells were positive
|
17
|
48
|
65
|
|
0.54 (0.26-1.14)
|
<0.01
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Zhou et al, 2009
|
10 percentile
|
72
|
8
|
80
|
|
0.41 (0.07-2.38)
|
0.042
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Randall et al, 2009
|
score=3
|
112
|
54
|
166
|
|
1.44 (0.70–2.75)
|
0.32
|
|
N/A
|
N/A
|
|
1.30 (0.67–2.54)
|
0.44
|
Yang et al, 2009
|
moderate staining
|
25
|
45
|
70
|
|
N/A
|
N/A
|
|
0.77 (0.18-3.42)
|
0.012
|
|
N/A
|
N/A
|
Secord et al, 2007
|
Median
|
32
|
35
|
67
|
|
1.93 (1.12-3.32)
|
0.018
|
|
N/A
|
N/A
|
|
2.19 (1.29-3.71)
|
0.004
|
Wada et al, 2006
|
score=2
|
9
|
51
|
60
|
|
N/A
|
N/A
|
|
2.85 (1.05-7.72)
|
0.689
|
|
N/A
|
N/A
|
Sutton et al, 2005
|
Median
|
45
|
137
|
182
|
|
1.82 (1.0-3.1)
|
0.01
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Fontana et al, 2005
|
positive
|
54
|
23
|
77
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
|
2.25 (0.81-6.27)
|
0.07
|
Poon et al, 2004
|
0.75
|
15
|
45
|
60
|
|
2.49 (0.63-9.86)
|
0.014
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Aishima et al, 2002
|
50% of the cells were positive
|
34
|
33
|
67
|
|
1.39 (0.70-2.78)
|
0.08
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Maeda et al, 2001
|
positive
|
89
|
61
|
150
|
|
N/A
|
N/A
|
|
2.37 (1.41-3.83)
|
0.03
|
|
N/A
|
N/A
|
Straume et al, 2001
|
moderate staining
|
77
|
104
|
181
|
|
2.07 (1.27-3.40)
|
0.0001
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Kodama et al, 2001
|
positive
|
31
|
23
|
54
|
|
N/A
|
N/A
|
|
3.16 (1.25-7.98)
|
0.015
|
|
N/A
|
N/A
|
You et al, 2000
|
5% of the cells were positive
|
29
|
10
|
39
|
|
1.49 (0.48-4.58)
|
0.0163
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
Yao et al, 2000
|
moderate staining
|
22
|
32
|
54
|
|
0.81 (0.14-4.58)
|
0.045
|
|
N/A
|
N/A
|
|
N/A
|
N/A
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
OS, overall survival; DFS, disease-free survival; MFS, metastasis-free survival; RFS, recurrence-free survival; PFS, progression-free survival; HR, hazard ratio; CI, confidence interval; N/A, not available.
OS associated with TSP-1 expression
Because of the mild heterogeneity (p=0.016, I2=47.3), the fixed effect model was used for data analysis. The results showed that high level of TSP-1 indicated poor OS, (HR=1.40; 95% CI: 1.17~1.68) and the effect was statistically significant (P<0.001) (Figure 2A). In order to analyze the source of heterogeneity, we did subgroup analyses according to nationality, dominant ethnicity, main pathological type, disease type, assay method and source of HR. When stratified by ethnicity, we found that the high level of TSP-1 was significantly correlated with the OS of Caucasians (HR=1.74; 95%CI: 1.37-2.22; P<0.001), while among Asians, there was no significant correlation (HR=1.07, 95%CI: 0.82-1.40; P=0.629) (Figure 3A). In the source of HR analysis, the OS of “reported” group was significantly worse(HR=1.48; 95%CI: 1.18~1.87; P=0.001), while the OS of the other group was also worse, however, with no statistical significance(HR=1.29; 95%CI: 0.97~1.171; P=0.081) (Figure 3B). According to the subgroup analysis of disease type, the pooled HR of breast cancer was 1.78(95%CI: 1.09~2.92; P=0.022) (I2=0.0%, P=0.536), and the pooled HR of gynecological cancer was 1.72(95%CI:1.13-2.64; P=0.012)(I2=0.0%, P=0.511), with no heterogeneity (Figure 3C). Finally, there was a significant relationship between elevated TSP-1 and poor OS in Americans. (HR=1.72; 95%CI: 1.13-2.64; P=0.012) (Figure 3E). Other kinds of diseases had no obvious significance.
PFS/MFS and DFS/RFS associated with TSP-1 expression
Six studies were included in the PFS/MFS analysis, in which a random-effect model was used due to the significant heterogeneity (p=0.006, I2=69.2) (Figure 2B). Our outcomes showed that there was no significant correlation between TSP-1 and PFS/MFS (HR=1.35; 95%CI: 0.87-2.10; P=0.176). Likewise, subgroup analyses were stratified for the PFS/MFS group to determine the potential source of heterogeneity and other significant information. In ethnicity subgroup, high expression of TSP-1 was related to unfavorable PFS/MFS in Caucasians (HR = 1.80, 95%CI: 1.34–2.40; P<0.001) (Figure 4A). Stratifying by the source of HR, high TSP-1 expression revealed a significant relationship with poor PFS/MFS, mainly in the report group (HR = 1.63, 95%CI: 1.24–2.15; P=0.001) but not in the SC group (Figure 4B). The subgroup analysis of cancer type indicated that TSP-1 have a statistically significant association with the breast cancer group (HR = 1.80, 95%CI: 1.20–2.71; P=0.004) and gynecologic cancer group (HR = 1.79, 95%CI: 1.18–2.71; P=0.006) (Figure 4C). when stratified by main pathological type, analysis in the adenocarcinoma group exhibited a significant correlation between up-regulated expression of TSP-1 and PFS/MFS (HR = 1.80, 95%CI: 1.20–2.71; P=0.004) (Figure 4D). Elevated TSP-1 predict poorer PFS/MFS in patients in the USA group (HR = 1.79, 95%CI: 1.18–2.71; P=0.006) (Figure 4E).
We analyzed tumor recurrence associated with overexpression of TSP-1 by DFS/RFS. Seven studies focused on DFS/RFS analysis, with a high degree of heterogeneity (P=0.001, I2=73.7) (Figure 2C).There was no correlation between high level of TSP-1 and poor DFS/RFS, (HR = 1.40, 95%CI: 0.77–2.53; P=0.271) by random effect model. Furthermore, through the subgroup analyses, we did not observe statistically significant outcomes (Figure S1). In summary, no relationship was found between DFS/RFS and TSP-1.
Cumulative meta-analysis
The main function of cumulative meta-analysis is reflecting the dynamic trend of the research results and evaluating the impact of each research on the comprehensive results. All the selected studies were sorted according to the year of publication. (Figure 5). The relationship between OS and TSP-1 was first statistically significant in 2001. In addition, the corresponding 95% CIs of OS became narrower with the continuous inclusion of studies, suggesting increasing estimated accuracy. On the contrary, as time goes on, the relationship of TSP-1 and DFS/RFS or PFS/MFS are no longer statistically significant, indicating growing controversy in recent research.
Publication bias
Egger’s test and Begg’s funnel plot were applied to indicate publication bias in the included studies (Figure S2). No obvious asymmetry was observed in funnel plots and the P value of Egger’s test also showed no obvious publication bias. (OS: P = 0.066; DFS/RFS: P =0.934; PFS/MFS: P =0.713).
Sensitivity analysis
In order to ensure the robustness of the above results and evaluate the stability of results, a sensitivity analysis was performed by Stata 12.0 software. The analyzed result from a fixed model of OS and two random model of DFS/RFS and PFS/MFS demonstrated that no single study considerably influenced the pooled HRs or 95% CIs, suggesting that the results of the present meta-analysis are credible (Figure 6).