TAS2R38 Bitterness Receptor Genetic Variation and Risk of Gastrointestinal Neoplasm: A Meta-Analysis

Figures & data

Figure 1. A flow chart depicting the literature search and study selection for the present meta-analysis.

Table 1. Summary of the key characteristics of the studies included in this meta-analysis.

Author (publication year)	Study place	Ethnicity	Neoplasm type	Number of cases/controls^a	Diplotype (case)			Diplotype (control)			Haplotype frequency (PAV)^b		Reference
					PAV/PAV	PAV/AVI	AVI/AVI	PAV/PAV	PAV/AVI	AVI/AVI	Case	Control
Carrai_Czech (2011)	Europe	Caucasian	CRC	479/509	93	210	176	95	259	155	0.413	0.441	3
3Carrai_German (2011)	Europe	Caucasian	CRC	413/609	62	190	161	118	293	198	0.380	0.434	3
Choi (2017)	Korea	Asian	CRC	680/1356	251	337	92	475	644	237	0.617	0.588	7,18
Choi (2016)	Korea	Asian	GC	447/1131	138	243	66	412	521	198	0.581	0.595	19
Schembre_Japanese (2013)	USA	Asian	AP	290/387	98	138	54	122	183	82	0.576	0.552	17
Schembre_Caucasian (2013)	USA	Caucasian	AP	385/510	85	170	130	92	236	182	0.442	0.412	17
Schembre_Hawaiian (2013)	USA	Polynesian	AP	187/226	75	95	27	98	104	24	0.622	0.664	17
Yamaki (2017)	Japan	Asian	GIC	79/180	18	39	22	66	90	30	0.475	0.597	20

CRC, colorectal cancer; GC, gastric cancer; AP, adenomatous polyp; GIC, gastrointestinal cancer.

a Number of subjects with PAV and AVI haplotypes, otherwise excluded due to the rarity.

b Distribution of genotypes in controls were all in Hardy-Weinberg equilibrium.

Figure 2. Odds ratios (ORs) and 95% confidence intervals (CIs) from analyzed studies comparing gastrointestinal neoplasms and the TAS2R38 haplotype (AVI vs. PAV) using a fixed effect model. The summarized OR is exhibited using a diamond. The center and both terminals of the diamond indicate the OR and 95% CI, respectively.

Figure 3. Odds ratios (ORs) and 95% confidence intervals (CIs) from studies comparing gastrointestinal neoplasms and the TAS2R38 diplotype (AVI/PAV vs. PAV/PAV) using a fixed effect model. The summarized OR is exhibited using a diamond. The center and both terminals of the diamond indicate the OR and 95% CI, respectively.

Figure 4. Odds ratios (ORs) and 95% confidence intervals (CIs) from studies comparing gastrointestinal neoplasms and the TAS2R38 diplotype (AVI/* vs. PAV/PAV) using a fixed effect model. The summarized OR is exhibited using a diamond. The center and both terminals of the diamond indicate the OR and 95% CI, respectively

Table 2. Stratified analyses of the effect of the TAS2R38 diplotype (AVI/AVI vs. PAV/PAV or PAV/*) on the risk of gastrointestinal neoplasms.

	N^a	AVI/AVI vs. PAV/PAV		AVI/AVI vs. PAV/*
		OR (95% CI)	P^b	OR (95% CI)	P
Total	8	1.067 (0.838–1.360)	0.006	1.055 (0.855–1.301)	0.002
Ethnicity
Caucasian	3	1.116 (0.755–1.648)	0.034	1.178 (0.931–1.491)	0.099
Non-Caucasian	5	1.043 (0.747–1.455)	0.023	1.055 (0.855–1.301)	0.032
Neoplasm type
Only GIC (excluding AP)	5	1.166 (0.833–1.631)	0.004	1.102 (0.813–1.494)	0.001
AP	3	0.880 (0.681–1.137)	0.207	0.949 (0.770–1.171)	0.338
CRC (including AP)	6	1.006 (0.769–1.317)	0.013	1.044 (0.830–1.314)	0.007
CRC (excluding AP)	3	1.083 (0.694–1.688)	0.005	1.091 (0.743–1.601)	0.002

OR, odds ratio; 95%CI, 95% confidence interval; GIC, gastrointestinal cancer; AP, adenomatous polyp; CRC, colorectal cancer.

A random effects model was applied when the P-value for heterogeneity <0.05 and I² > 50%; otherwise, a fixed effects model was used.

a Number of studies.

b P value of Q test to assess heterogeneity.

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