Significant oral cancer risk associated with low socioeconomic status.
METHODS
Searches were made for studies in Medline, Medline In-Process and other Non-indexed Citations Embase, CINAHL, PsychINFO, CAB Abstracts 1973-date, EBM Reviews, ACP Journal Club, Cochrane Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Management Information Consortium database and Pubmed. Un-published data were also received from the International Head and Neck Cancer Epidemiology Consortium.


METHODS
Studies were identified independently by two reviewers and were included if their subject was oral and/ or oropharyngeal cancer; they used case-control methodology; gave data regarding socioeconomic status (SES; eg, educational attainment, occupational social classification or income) for both cases and controls; and the odds ratio (OR) for any SES measure was presented or could be calculated. Corresponding authors were contacted where there was an indication that data on oral and/ or oropharyngeal cancers could potentially be obtained from the wider cancer definition or grouping presented in the article, or if SES data were collected but had not been presented in the article. Methodological assessment of selected studies was undertaken.


METHODS
Countries where the study was undertaken were classified according to level of development and income as defined by the World Bank. Where available the adjusted OR (or crude OR) with corresponding 95% confidence intervals (CI) were extracted, or were calculated for low compared with high SES categories. Meta-analyses were performed on the following subgroups: SES measure, age, sex, global region, development level, time-period and lifestyle factor adjustments. Sensitivity analyses were conducted based on study methodological issues. Publication bias was assessed using a funnel plot.


RESULTS
Forty-one studies met the inclusion criteria and yielded 15,344 cases and 33,852 controls. Compared with individuals who were in high SES strata, the pooled OR for the risk of developing oral cancer were 1.85 (95% CI, 1.60-2.15; N=37 studies) for individuals with low educational attainment versus 1.84 (95% CI, 1.47-2.31; N=14) for those with low occupational social class versus and 2.41 (95% CI, 1.59-3.65; N=5) for people with low incomes. Subgroup analyses showed that low SES was significantly associated with increased oral cancer risk in high- and lower-income countries, across the world, and remained when adjusting for potential behavioural confounders.


CONCLUSIONS
Oral cancer risk associated with low SES is significant and related to lifestyle risk factors. These results provide evidence to steer
Warnakulasuriya
Saman
S
Department of Oral Medicine, World Health Organization Collaborating Centre for Oral Cancer, King's College London Dental Institute, London, UK.