Meta-Analysis
Copyright ©The Author(s) 2024.
World J Gastrointest Surg. Feb 27, 2024; 16(2): 585-595
Published online Feb 27, 2024. doi: 10.4240/wjgs.v16.i2.585
Table 1 Baseline characteristics of included studies
Ref.
Country
Study date
Patients
Study type
Follow-up
Diagnosis of gastric cancer
Definition of oral health
NOS
Watabe et al[32], 1998JapanOctober 1996 to September 1997242Retrospective cohort studyNAGastric cancerBrush teeth, decayed teeth, gingivitis, bad occlusion, dentures (partial and full), and lack of teeth ≥ 106
Abnet et al[27], 2001ChinaMarch 1986 to May 199128868Prospective cohort study5.25 yrGastric cardia tumor and non-cardia tumorTooth loss8
Hujoel et al[20], 2003United States1971 to 199211328Prospective cohort studyUntil 1992Gastric cancer (ICD-9 151.0-151.9)Periodontitis, gingivitis, and edentulism7
Abnet et al[28], 2005Finland1985 to 199929124Prospective cohort studyApril 1993 to April 1999Gastric non-cardia adenocarcinomaTooth loss included 0-10 teeth lost, 11-31 teeth lost, and edentulous8
Michaud et al[29], 2008United States1986 to January 200449375Prospective cohort studyMedian of 17.7 yrGastric cancerPeriodontal disease and tooth loss9
Hiraki et al[19], 2008Japan2000 to 200515720Case-control studyNAGastric cancer (ICD-10 C16)Remaining teeth7
Shakeri et al[31], 2013IranJanuary 2004 to June 2008922Case-control studyDecember 2004 to December 2011Gastric adenocarcinoma included non-cardia, cardia, and mixed-locationsTooth loss, decayed, missing, filled teeth score, and frequency of tooth brushing6
Ndegwa et al[30], 2018Sweden1973 to 197419831Prospective cohort study569233 person-yearsGastric cancer was divided into cardia (ICD 151.1) and non-cardia gastric cancer (all ICD-7 151 codes except ICD 151.1)Number of teeth, dental plaque status, and presence of any oral mucosal lesions7
Yano et al[33], 2021IranJanuary 2004 to June 200850045Prospective cohort studyUntil December 31, 2019Gastric cancer cases were limited to adenocarcinomas (cardia and non-cardia)Frequency of tooth brushing, tooth loss, and the sum of decayed, missing, or filled teeth9
Zhang et al[8], 2022ChinaOctober 2010 to September 20132873Case-controlNAGastric cancer was divided into esophagogastric junction cancer and total gastric cancerTooth loss after 20 yr, number of tooth loss after age 20 yr, age of first tooth loss after age 20 yr, denture wearing, number of filled teeth, missing and filled teeth, frequency of toothbrushing, frequency of oral discomfort while eating, avoidance of some foods because of oral problems6
Zhang et al[34], 2022China2004 to 2008510148Prospective cohort studyMedian of 9.17 yr and range of 0.1 to 11.5 yrGastric cancer (ICD-10 C16)Gum bleeding and rarely or never brush teeth9
Kim et al[21], 2022South KoreaJanuary 2003 to December 2015713201Retrospective cohort studyUp to 10 yrGastric cancer (ICD-10 C16)Periodontitis (who visited a dental clinic two or more than two times within one year and were diagnosed with periodontitis under those ICD-10 codes (K05.2, K05.3, K05.4, K05.5, and K05.6)9
ICD: International Classification of Diseases; NA: Not available; NOS: Newcastle-Ottawa Scale.
Table 2 Results of quality assessment using the Newcastle-Ottawa Scale for cohort studies
Ref.
Selection
Comparability
Outcome
Scores
Representativeness of exposure
Selection of the non-exposure
Ascertainment of exposure
Demonstration that outcome was not present at start
Cohorts on the basis of the design or analysis
Assessment
Long follow-up for outcomes to occur
Adequacy of follow-up
Abnet et al[28], 2005★★★★★★☆★★8
Abnet et al[27], 2001☆★★★★★★★★8
Hiraki et al[19], 2008★★★★★★★☆☆7
Hujoel et al[20], 2003★★★★★★★☆☆7
Kim et al[21], 2022★★★★★★★★★9
Michaud et al[29], 2008★★★★★★★★★9
Ndegwa et al[30], 2018☆☆★★★★★★★7
Watabe et al[32], 1998☆★★★★★★☆☆6
Yano et al[33], 2021★★★★★★★★★9
Table 3 Results of quality assessment using the Newcastle-Ottawa Scale for case-control studies
Ref.
Selection
Comparability
Exposure
Scores
Adequate definition of cases
Representativeness of the cases
Selection of controls
Definition of controls
Control for important factor1
Ascertainment of exposure
Same method of ascertainment for cases and controls
Non-response rate
Shakeri et al[31], 2013★☆☆★★★☆★★6
Zhang et al[8], 2022★☆☆★★★★★☆6
Zhang et al[34], 2022★★★★★★★★★9
1A maximum of 2 stars can be allotted in this category, one for age, the other for other controlled factors.
Table 4 The analyses were adjusted for the following variables
Ref.
Variables of adjustment
Abnet et al[28], 2005Age and education
Abnet et al[27], 2001Age, sex, tobacco use, and alcohol use
Hiraki et al[19], 2008Age, sex, smoking and drinking status (never, former, current), vegetable and fruit intake, BMI, and regular exercise
Hujoel et al[20], 2003Age and gender
Kim et al[21], 2022Age
Michaud et al[29], 2008Age (continuous), ethnic origin (white, Asian, black), physical activity (quintiles), history of diabetes (yes or no), alcohol (quartiles), BMI (< 22, 22-24.9, 25-29.9, 30 +), geographical location (south, west, northeast, mid-west), height (quintiles), calcium intake (quintiles), total calorific intake (quintiles), red-meat intake (quintiles), fruit and vegetable intake (quintiles), vitamin D score (deciles), smoking history (never, past quit ≤ 10 yr, past quit > 10 yr, current 1-14 cigarettes per day, 15-24 cigarettes per day, 25 + cigarettes per day), and pack-years (continuous)
Ndegwa et al[30], 2018Age as time-scale, age at entry, sex, area of residence (rural, small-town or urban), tobacco use status (non-tobacco use, smoking only, snus only or mixed usage), and alcohol consumption (less than once a week versus once a week or more)
Shakeri et al[31], 2013Age, ethnicity, education, fruit and vegetable use, socioeconomic status, ever opium or tobacco use, and denture use
Watabe et al[32], 1998NA
Yano et al[33], 2021Age, sex, socioeconomic score, ethnicity, residence, education, cigarette use, and opium use
Zhang et al[8], 2022Age (continuous), sex, education (illiteracy, primary school, junior school, high school and above), marital status (single, married, divorced or widowed), job type (farmer, worker, others), wealth score (five levels), BMI 10 years ago (< 18.5 kg/m2, 1.85 to 24.0 kg/m2, 24.0 to 28.0 kg/m2, ≥ 28.0 kg/m2), tobacco smoking (never, ≤ 30 pack-years, > 30 pack-years), alcohol drinking (never, ≤ 80 g/d, > 80 g/d), H. pylori seropositivity (yes/no), and family history of GC (yes/no)
Zhang et al[34], 2022Age (continuous), sex (male, female), BMI (continuous), study sites (10 sites), education level (no formal school, primary or middle school, high school and above), marital status (married, other), household income per year (< 10000, < 10000-19999, < 20000-34999, or < 35000), alcohol consumption (non-drinker, occasional drinker, former drinker, or regular drinker), smoking status (never smoker, occasional smoker, former smoker, or regular smoker), physical activity in MET hours a day (continuous), aspirin prescription for CVD (no, yes, or missing), menopausal status (pre-menopausal or post-menopausal, women only), personal history of diabetes (no, yes), and family history of cancer (no, yes)
BMI: Body mass index; MET: Metabolic equivalent tasks; CVD: Cardiovascular disease; NA: Not applicable; H. pylori: Helicobacter pylori; GC: Gastric cancer.