Opium Use and Cancer Risk: A Comprehensive Systematic Review and Meta-Analysis of Observational Studies
Table 1
Subgroup analyses for the association between opium use and cancer risk in adults aged ≥18 years.
#ES1
Pooled ES (95% CI)2
3
I2 (%)4
-heterogeneity5
Ever versus never use of opium and cancer
Overall
20
3.53 (2.60–4.79)
≤0.01
89.5
≤0.01
Subgroup analysis
Study design
Cohort
Case-control
2
1.86 (0.79–4.39)
0.15
75.3
0.04
Cancer type
18
3.71 (2.93–4.70)
≤0.01
73.8
≤0.01
GI
12
2.49 (1.81–3.43)
≤0.01
77.5
≤0.01
Bladder
6
3.85 (2.96–5.00)
≤0.01
26.9
0.23
Lung
3
5.00 (2.70–9.28)
≤0.01
66.2
0.05
Head and neck
3
4.35 (2.61–7.26)
≤0.01
60.3
0.08
Larynx
5
8.85 (6.16–12.74)
≤0.01
24.5
0.25
Oral
3
1.81 (1.23–2.65)
≤0.01
9.7
0.33
Pancreas
2
2.14 (1.37–3.36)
≤0.01
0
0.55
Esophageal
3
2.05 (0.93–4.55)
0.08
62.3
0.07
Colorectal
2
4.49 (2.81–7.16)
≤0.01
0
0.99
Colon
3
3.01 (0.89–10.11)
0.07
84.9
≤0.01
Gastric
4
2.38 (1.40–4.06)
≤0.01
74.0
≤0.01
Cancer assessment
Medical records
6
4.27 (2.99–6.10)
≤0.01
33.8
0.18
Histological/pathological methods
14
3.24 (2.24–4.69)
≤0.01
92.0
≤0.01
Adjustment for tobacco use
Yes
16
3.32 (2.35–4.69)
≤0.01
91.0
≤0.01
No
4
4.40 (2.63–7.36)
≤0.01
57.4
0.07
Adjustment for dietary factors
Yes
9
4.35 (3.43–5.51)
≤0.01
0
0.62
No
11
2.97 (1.96–4.50)
≤0.01
93.6
≤0.01
Study quality
High
15
3.18 (2.27–4.45)
≤0.01
90.5
≤0.01
Low
5
5.03 (2.43–10.43)
≤0.01
79.5
≤0.01
Highest versus lowest doses of opium use and cancer
Overall
10
4.29 (2.15–8.54)
≤0.01
82.7
≤0.01
Subgroup analyses
Cancer type
GI
7
2.82 (1.31–6.05)
≤0.01
74.4
≤0.01
Lung
2
10.06 (3.84–26.35)
≤0.01
0
0.90
Head and neck
2
2.79 (0.28–27.88)
0.38
95.9
≤0.01
Larynx
2
3.33 (0.25–44.05)
0.36
95.5
≤0.01
Oral
2
0.86 (0.35–2.10)
0.73
0
0.33
Colorectal
2
7.40 (3.28–16.71)
≤0.01
0
0.81
Colon
2
8.34 (3.54–19.63)
≤0.01
0
0.77
Cancer assessment
Medical records
5
8.15 (5.02–13.24)
≤0.01
0
0.40
Histological/pathological methods
5
2.47 (1.09–5.58)
0.03
81.1
≤0.01
Adjustment for tobacco use
Yes
7
3.80 (1.44–10.02)
≤0.01
83.4
≤0.01
No
3
5.66 (1.92–16.63)
≤0.01
81.9
≤0.01
Adjustment for dietary factors
Yes
6
7.94 (5.03–12.51)
≤0.01
0
0.53
No
4
2.04 (0.86–4.85)
0.10
82.6
≤0.01
Study quality
High
9
3.87 (1.91–7.88)
≤0.01
80.9
≤0.01
Low
1
9.22 (4.19–20.28)
≤0.01
—
—
Duration of opium use and cancer risk
Overall
11
3.74 (2.41–5.82)
≤0.01
75.8
≤0.01
Subgroup analysis
Study design
Cohort
Case-control
1
1.81 (1.27–2.57)
≤0.01
—
—
Cancer type
10
4.23 (2.55–7.02)
≤0.01
74.8
≤0.01
GI
8
2.86 (1.69–4.83)
≤0.01
71.8
≤0.01
Lung
3
3.95 (2.37–6.60)
≤0.01
0
0.77
Head and neck
2
5.50 (1.09–27.72)
0.04
89.9
≤0.01
Larynx
2
5.77 (1.19–28.11)
0.03
87.4
≤0.01
Oral
2
2.03 (0.87–4.75)
0.10
0
0.91
Colorectal
2
6.99 (3.68–13.28)
≤0.01
0
0.61
Colon
2
8.24 (3.50–19.38)
≤0.01
0
0.80
Cancer assessment
Medical records
5
9.26 (5.60–15.29)
≤0.01
0
0.81
Histological/pathological methods
6
2.25 (1.62–3.11)
≤0.01
52.3
0.06
Adjustment for tobacco use
Yes
9
3.19 (2.05–4.97)
≤0.01
70.2
≤0.01
No
2
6.47 (1.74–24.03)
≤0.01
82.2
0.01
Adjustment for dietary factors
Yes
6
8.34 (5.37–13.08)
≤0.01
0
0.81
No
5
2.02 (1.54–2.64)
≤0.01
31.1
0.21
Study quality
High
10
3.18 (2.13–4.74)
≤0.01
68.1
≤0.01
Low
1
13.16 (5.32–32.54)
≤0.01
—
—
Opium smoking versus never use
Overall
5
2.43 (1.46–4.04)
≤0.01
92.2
≤0.01
Cancer type
GI
4
1.47 (1.07–2.02)
0.01
52.1
0.10
Bladder
2
3.55 (2.59–4.86)
≤0.01
0
0.36
Lung
2
3.00 (1.12–7.98)
0.02
70.7
0.06
Head and neck
2
1.45 (0.40–5.35)
0.57
88.4
≤0.01
Larynx
2
3.66 (2.24–5.97)
≤0.01
34.6
0.21
Oral
3
1.71 (0.88–3.32)
0.11
58.0
0.09
Opium ingestion versus never use and cancer
Overall
5
2.66 (1.40–5.07)
≤0.01
92.5
≤0.01
Cancer type
GI
4
1.82 (1.15–2.89)
0.01
47.4
0.12
Bladder
2
4.02 (2.96–5.47)
≤0.01
0
0.75
Lung
2
2.00 (1.05–3.83)
0.03
54.0
0.14
Head and neck
2
4.29 (1.11–16.62)
0.03
86.8
≤0.01
Larynx
2
6.82 (1.05–44.17)
0.04
89.6
≤0.01
Oral
3
2.59 (0.92–7.29)
0.07
20.7
0.28
Teriak use versus never use and cancer
Overall
3
1.98 (1.08–3.62)
0.03
94.8
≤0.01
Cancer type
GI
3
1.98 (1.08–3.62)
0.03
94.8
≤0.01
Head and neck
2
2.08 (0.73–5.89)
0.16
89.4
≤0.01
Larynx
2
3.97 (1.69–9.36)
≤0.01
76.4
0.04
Shireh use versus never use and cancer
Overall
3
3.03 (0.82–11.14)
0.10
94.6
≤0.01
Cancer type
GI
3
3.03 (0.82–11.14)
0.10
94.6
≤0.01
Larynx
2
7.54 (2.13–26.63)
≤0.01
69.7
0.07
GI: gastrointestinal, ES: effect size; 1number of effect sizes; 2obtained from the random-effects model; 3overall effect sizes, and 4inconsistency, the percentage of variation across studies due to heterogeneity; 5obtained from the Q-test.
