Alcohol consumption and risk of laryngeal cancer

Summary

Epidemiological studies consistently showed that alcohol drinking increases the risk of laryngeal cancer. This risk increases with the amount of alcohol consumed: in recent studies conducted in North America, Europe, Japan and Korea the multivariate relative risks for the highest levels of consumption ranged between 2 and 10, and were 1.94 for 50 g/day and 3.95 for 100 g/day in a meta-analysis of 20 studies. Further, the risk increases by concomitant tobacco smoking, each agent approximately multiplying the effect of the other. In the absence of smoking the risks are small for moderate alcohol consumption. After stopping drinking, some fall in risk becomes apparent in the long term. The role of age at starting and stopping drinking is still unclear. In various studies, the most commonly used alcoholic beverage appears to be the most associated with laryngeal cancer risk, suggesting that no meaningful difference exists for different types of alcoholic beverages. The supraglottis is more closely related to alcohol consumption, as compared to the glottis/subglottis. Alcohol drinking may influence laryngeal cancer risk particularly through its direct contact or solvent action, perhaps by enhancing the effects of tobacco or other environmental carcinogens.

Introduction

Alcohol and tobacco are the two best recognized risk factors for cancer of the larynx, and account for the vast majority of cases in developed countries.1, 2, 3 A relation between intake of alcoholic beverages and the development of cancer of the larynx was firstly suggested in the early 1900s by occupational mortality statistics and clinical reports, and was subsequently supported by ecological studies comparing per capita alcohol consumption and trends in laryngeal cancer incidence and mortality.4, 5, 6, 7, 8 However, the definition of alcohol as an independent etiologic factor for laryngeal cancer was not obtained, until the late 1950s and early 1960s, with the development of ad hoc epidemiological investigations.9, 10, 11

Epidemiological studies—mainly case–control ones—conducted since then consistently found an independent dose–response association of alcohol drinking with laryngeal cancer risk and a synergistic effect with tobacco smoking.² The studies published until 1988 were systematically reviewed in a Monograph of the International Agency for Research on Cancer.¹² Data included in the Monograph were provided from six prospective studies, five of alcoholics and one of brewery workers. All these studies except one showed 2- to 5-fold increased risks. Moreover, 14 case–control studies conducted in North America and Europe showed an increased risk for alcohol drinkers, with a trend in risk for amount of alcohol intake, and no indication of a different risk for various types of alcoholic beverages. Thus, the IARC Working Group concluded that the occurrence of cancer of the larynx was causally related to the consumption of alcoholic beverages.¹²

Several important aspects of the relation between alcohol drinking and laryngeal cancer risk remained however unsettled. These included the role of time-related variables, such as duration of the habit, age at starting, time since cessation, and the effect of different types of alcoholic beverages. Further, the risk may differ by laryngeal anatomical subsites, such as the supraglottis and the glottis/subglottis.

The epidemiological evidence on the association between alcohol consumption and laryngeal cancer risk will be reviewed, with particular focus to more recent works and these open issues. Epidemiological studies were identified through Medline and by searching the references of the retrieved studies. For total alcohol drinking only studies published after 1988 were included; for specific topics—on which fewer studies have been published—results from older studies have also been included and discussed.