Elsevier

Oral Oncology

Volume 46, Issue 10, October 2010, Pages 720-726
Oral Oncology

Review
A meta-analysis of alcohol drinking and oral and pharyngeal cancers. Part 2: Results by subsites

https://doi.org/10.1016/j.oraloncology.2010.07.010Get rights and content

Summary

Oral and pharyngeal cancers are strongly related to alcohol drinking. We combined findings from all case-control and cohort studies published up to September 2009 and presented analyses by subsites, using a meta-analytic approach. Summary measures were obtained using random-effects models, and taking into account the correlation between estimates from the same study. We also performed a dose-risk analysis, using a random-effects meta-regression model. Compared to non- or occasional drinkers, the overall relative risks (RR) for light drinkers were 1.17 (95% confidence interval, CI, 1.01–1.35) for oral (nine studies) and 1.23 (95% CI, 0.87–1.73) for pharyngeal (five studies) cancer, with no significant heterogeneity between the two sites (p = 0.793). RRs for heavy drinkers were 4.64 (95% CI, 3.78–5.70) for oral (17 studies) and 6.62 (95% CI, 4.72–9.29) for pharyngeal (17 studies) cancer (p of heterogeneity between the two sites = 0.075). The summary RRs for heavy drinkers were 4.11 (95% CI, 2.46–6.87) for tongue (five studies), 7.76 (95% CI, 4.77–12.62) for oropharyngeal (four studies), and 9.03 (95% CI, 4.46–18.27) for hypopharyngeal (four studies) cancer. In conclusion, the alcohol-related RRs are higher for pharyngeal than for oral cancer, particularly at higher doses, while the association with cancer of the tongue was similar to that for oral cancer.

Introduction

Alcohol drinking increases the risk of oral and pharyngeal cancers. In a recent meta-analysis, including 45 studies for a total of 17,085 cases, we estimated relative risks (RR) of 1.29 for 10, 3.24 for 50, 8.61 for 100, and to 13.02 for 125 g of ethanol per day for oral cavity and pharynx combined.1

However, the anatomic sites most strongly associated with alcohol drinking have varied from study to study. Thus, in a case-control study from four areas of the United States2 the association was less strong for tongue than for other oral sites or pharynx, particularly in men. In another case-control study, based on US Veterans,3 patients with cancer at the floor of the mouth and oral tongue had higher RRs than those with cancer at other oral and pharyngeal sites. In a study from Italy and Switzerland,4 the RRs were appreciably higher for oral than for pharyngeal cancer. In a study from Puerto Rico5 there was no significant difference among tongue, other oral and pharynx in both sexes. However, no single study had adequate power to test the possible differences in alcohol-related risks across subsites, and the apparent differences may be due to chance alone. Human papillomavirus (HPV) is related to a subset of cancers of the oropharynx.6, 7 However, in a study comparing HPV-associated with HPV-independent cancers, no appreciable difference was observed for the alcohol-related RRs.6

In order to provide a detailed quantification of the association of alcohol consumption with oral and pharyngeal cancer separately, as well as with subsites of the oral cavity and of the pharynx, we conducted a meta-analysis of studies published up to September 2009.

Section snippets

Identification of studies and collection of data

The methodology of identification of studies and collection of data has been previously described.1 Briefly, using PubMed, we performed a literature search of all case-control and cohort studies published up to September 2009 and presenting data on the association between alcohol and risk of oral and/or pharyngeal cancer, following the meta-analysis of observational studies in epidemiology (MOOSE) guidelines.8 We did not consider cancer of the nasopharynx, as it shows an epidemiology and

Results

The main characteristics of the studies have already been described.1 Appendix 1 reports the characteristics of the five additional studies not included in the previous review.1 The present analyses are based on 303, 4, 9, 10, 11, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 case-control and 117 cohort study. Some studies reported data for more than one anatomical site. Twenty-two reports3, 4, 11, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,

Discussion

In this meta-analysis, we found higher risk estimates for alcohol intake for pharyngeal (oro- and hypopharynx) as compared to oral (including tongue) cancer. There was, however, significant heterogeneity among studies.

We conducted several sensitivity analyses, which confirmed the stronger association of alcohol with pharyngeal rather than oral cancer. In particular, we found that the different effect of alcohol on oral and pharyngeal carcinogenesis persists even when only studies reporting risk

Conflict of interest statement

None declared.

Acknowledgments

This work was conducted with the contribution of the Italian Association for Cancer Research (AIRC). Irene Tramacere was supported by a fellowship from the Italian Foundation for Cancer Research (FIRC). The authors thanks Ms. I. Garimoldi for editorial assistance.

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