Occupational exposure to petroleum-based and oxygenated solvents and hypopharyngeal and laryngeal cancer in France: the ICARE study.

BACKGROUND: To examine associations between occupational exposure to petroleum-based and oxygenated solvents and the risk of hypopharyngeal and laryngeal cancer. METHODS: ICARE is a large, frequency-matched population-based case-control study conducted in France. Lifetime occupational history, tobacco smoking and alcohol consumption were collected. Analyses were restricted to men and included 383 cases of hypopharyngeal cancer, 454 cases of laryngeal cancer, and 2780 controls. Job-exposure matrices were used to assess exposure to five petroleum-based solvents (benzene; gasoline; white spirits; diesel, fuels and kerosene; special petroleum products) and to five oxygenated solvents (alcohols; ketones and esters; ethylene glycol; diethyl ether; tetrahydrofuran). Odds ratios (ORs) adjusted for smoking, alcohol drinking and other potential confounders and 95% confidence intervals (CI) were estimated with unconditional logistic models. RESULTS: No significant association was found between hypopharyngeal or laryngeal cancer risk and exposure to the solvents under study. Non-significantly elevated risks of hypopharyngeal cancer were found in men exposed to high cumulative levels of white spirits (OR = 1.46; 95% CI: 0.88-2.43) and tetrahydrofuran (OR = 2.63; 95CI%: 0.55-12.65), with some indication of a dose-response relationship (p for trend: 0.09 and 0.07 respectively). CONCLUSION: This study provides weak evidence for an association between hypopharyngeal cancer and exposure to white spirits and tetrahydrofuran, and overall does not suggest a substantial role of exposure to petroleum-based or oxygenated solvents in hypopharyngeal or laryngeal cancer risk.

Vitamin and carotenoid intake and risk of head-neck cancer subtypes in the Netherlands Cohort Study.

BACKGROUND: Head and neck cancer (HNC) is the seventh most-common type of cancer worldwide. Evidence regarding the potential protective effect of vitamins and carotenoids on HNC is limited and mostly based on case-control studies. OBJECTIVE: We evaluated the association of intake of dietary vitamins C and E (including supplementation) and the most-common carotenoids (α-carotene, ß-carotene, lutein plus zeaxanthin, lycopene, and ß-cryptoxanthin) and risk of HNC and HNC subtypes in a large prospective study. DESIGN: The Netherlands Cohort Study included 120,852 participants. For efficiency reasons, a case-cohort design was used. At baseline in 1986, participants completed a food-frequency questionnaire. A subcohort was randomly selected from the total cohort. After 20.3 y of follow-up, 3898 subcohort members and 415 HNC cases [131 oral cavity cancer (OCCs), 88 oro-/hypopharyngeal cancer (OHPs), and 193 laryngeal cancer cases] were available for analysis. Rate ratios and 95% CIs for highest (quartile 4) compared with lowest (quartile 1) quartiles of vitamin and carotenoid intake were estimated by using the Cox proportional hazards model. RESULTS: A strong inverse association was shown between vitamin C and HNC overall (multivariable-adjusted rate ratio for quartile 4 compared with quartile 1: 0.39; 95% CI: 0.23, 0.66; P-trend < 0.001), OCC (multivariable-adjusted rate ratio for quartile 4 compared with quartile 1: 0.35; 95% CI: 0.16, 0.77; P-trend < 0.05), and OHPC (multivariable-adjusted rate ratio for quartile 4 compared with quartile 1: 0.29; 95% CI: 0.12, 0.67; P-trend < 0.01). No statistically significant results were shown for vitamin E, α-carotene, ß-carotene, lycopene, and lutein plus zeaxanthin. The association of vitamin E and HNC was modified by alcohol status (P-interaction = 0.003) with lower risks in alcohol abstainers. CONCLUSIONS: With this study, we show an inverse association between intake of vitamin C and the incidence of HNC and HNC-subtypes. Future research is recommended to investigate the underlying mechanisms and to confirm our results, which may be promising for the prevention of HNC.

Nutrition and laryngeal cancer.

The main etiologic factors of cancers of the larynx and hypopharynx are alcohol and tobacco, and their prevalence in different populations explains, to a large extent, the wide variations in incidence observed around the world. Besides these two main risk factors, however, diet also seems to play a role in determining the risk of these cancers. There is consistent evidence that low consumption of fruit and vegetables is associated with higher risk, after statistical adjustment for alcohol and tobacco. Consumption of vegetable oils and fish and a moderately high polyunsaturated/saturated fatty acid ratio (P/S ratio) were reported to be associated with reduced risk. Low intake of vitamin C, beta-carotene and vitamin E were reported consistently to be associated with higher laryngeal cancer risk, but there was no clear evidence that these micronutrients are better predictors of cancer risk than the principal food groups from which their intake levels were estimated, i.e., fruits, vegetables, vegetable oils, and fish. Given the overwhelming role of tobacco and alcohol in the etiology of these cancers and the extremely low incidence among nonsmokers/nondrinkers, the available studies provide no estimate of the role of diet in subjects not exposed to these factors. The evidence indicates, however, that, in the presence of tobacco and/or alcohol, low intake of fruit and vegetables may account for 25 to 50 percent of the cases among men.