Although smoking and drinking alcohol are established risk factors for both lung and laryngeal cancer, dietary factors related to laryngeal cancer risk have been less frequently examined. Acase -control study of laryngeal cancer in white men in western New York analyzed the interaction of diet with smoking and alcohol (95). Case – patients consumedsignificantly more fat and kilocalories than controls; their intake of carotenoids and vitamin C tended to be less. Beer, hard liquor,and total alcohol intake were strongly associated with risk; wine intake were generally low and was not associated with risk. Cigarette smoking was also a major risk factor but use of carotenoids was most protective for light smokers, whereas risk associated with high intake of fat was greatest for heavy smokers. The relationship between carotenoid intake and risk was similar at high and low fat intakes, and conversely. High retinal intake was positively associated with risk in heavy drinkers; there was no interaction between retinal and carotenoids. When odds ratios were calculated for 129 individual foods, seven raw vegetables were significantly protective, whereas risk was positively associated with intake of mayonnaise, milk, doughnuts, veal, cooked peas, and cooked cauliflower, High total intake of raw vegetables was protective; high intake of milk and milk products increased risk. Overall, smoking was the overwhelming risk factor for laryngeal cancer. Dietary variables could modulate the effect of smoking, but their effect was much weaker.
A case – control study of laryngeal cancer in Shanghai again found cigarette smoking to be the most important risk factor (96). There was no dose-related effect of alcohol drinking on risk, but amounts of alcohol consumed were generally low. High in take of vegetables and fruits, particularly dark yellow and Allium vegetables (garlic and onions), was protective; high in take of live, salted fish, meat and eggs, and deep – fried foods increased risk. Some occupational risks were also identified , and elevated risk was linked to long-term use of kerosene stoves in cooking.
A prospective study of 4538 Finnish men evaluated the relationship between dietary cholesterol and fatty acids and lung cancer risk (97). During 20 years of follow-up, 117 cases of lung cancer were diagnosed. In take of total and saturated fats was nonsignificantly related to risk, but no increased risk was associated with cholesterol intake. As with laryngeal cancer, the effect of fat was dwarfed by the risk associated with smoking and was mainly seen in smokers. In comparing populations whose dietary habits differ widely, however, the importance of diet is more readily seen. American men have much higher lung cancer mortality rate than Japanese (72.2 vs. 38.2 per 100,000 in 1985) (98). Nevertheless, the proportion of smokers is higher in Japan that in the USA, and although the Japanese tend to begin smoking at a later age they smoke more cigarettes per day. There are a later age they smoke more cigarettes per day. There are no important differences inhalation patterns and type of cigarette smoked. Differences and changes in consumption of fruits and vegetables in the two countries are too small to affect lung cancer mortality, but the difference in fat consumption is striking: in 1950 and 1985 respectively, 40% and 43.5%(USA)vs. 7.9 % and 24.5% (Japan). The authors summarized mechanisms by which fat is thought to promote cancer through actions on endocrine, autocrine, and immune systems, oncogenes, gut bacteria, membrane structure, and lipid proxides.
There were several reports that high intake of fruits and vegetable protects against lung cancer (99-101). When the relationship between dietary antioxidants and risk of lung cancer was examined in the Finnish cohort described in reference 97, nonsignificant protective effects were found for carotenoids, vitamin E , and vitamin C in nonsmokers (99). In the total cohort, margarine and fruit were significantly protective, although again the effect was stronger in nonsmokers. The relative risk for the lowest quartile of margarine intake, compared with the highest, was 4.0 (p<.001) and for fruits was 1.8 (p=.05). The authors suggest that food sources rich in carotenoids, vitamin C, and vitamin E have other constituents with independent protective effects against lung cancer. A nested case-control study in a cohort of 41,837 women in the Iowa Women’s Health Study found that the 101 case- patients consumed significantly less tomatoes, green leafy vegetables, fruit, and all fruits and vegetables (100). The associations did not differ by smoking status, and no association was found with intake of β-carotene. Among tin miners of the Yunnan Province, China, exposure radon and arsenic increases risk of lung cancer (101). To learn whether diet affects this risk, 183 miners with newly diagnosed lung cancer and 183 age-matched occupational controls were interviewed about heir usual diet and smoking history. Miners who reported a low intake of yellow and light-green vegetables or tomatoes were at significantly greater risk for lung cancer after adjustment for radon, arsenic, and smoking. There was a monotonic relationship between quartile of intake and odds ratio for lung cancer.
Because of reports associating dietary cholesterol with lung cancer incidence, a cohort of 1878 middle-aged men who in 1958 were employed by the Western Electric Company in Chicago was followed for 24 years, to determine whether cholesterol intake was related o lung cancer in that population (102). After adjustment for smoking, age, and intake of β-carotene and fat, the relative risk of lung cancer associated with a 500 mg/day increment of dietary cholesterol was 1.9 The association persisted after adjustmen for serum cholesterol and dietary fat. Moreover, it seemed o be specific o cholesterol from eggs. Mean values for dietary cholesterol from eggs and other sources were 238 and 491 mg/day, respectively, but 11 other foods or food groups that could provide appreciable amounts of cholesterol were not significantly associated with lung cancer risk. One interpretation of these results is that something associated with eggs besides cholesterol is a risk factor for lung cancer. However, reanalysis of data from a case-control sudy in Hawaii to look for an “egg effect” failed to corroborate the findings of the Western Electric study (103). There was a significant positive trend of the odd ratio with increasing consumption of total cholesterol and cholesterol from sources other than eggs for men but not women.
The mortality rates of lung cancer were greater in the north of Italy than in the south in 1980 and 1982, although the proportions of smokers, surveyed in 1977, were similar (104). Information on dietary habits derived from annual surveys conducted form 1960 through 1965 showed hat the diet in southern Italy contained less saturated and polyunsaturated fat and more foods of plant origin than the diet in northern Italy.
The lung cancer rate among men in Gejiu City, Yunnan Province, China, is one of the highest in the world (105). In this in-mining community, rice is the dietary staple and bean curd is the primary source of additional protein. A case-control study of diet and lung cancer risk was conducted because it was thought that in this situation the simplicity and relative homogeneity of the diet serve to highlight links between die and lung cancer. Where possible, each case-subject was matched with a miner control and a Gejiu City control and was queried about usual frequency of intake of 31 food items and food groups. Case-subjects ate rice and noodles some what more often than controls, but ate most other items less often. The difference were significant for bean curd, meat (pork), eggs, fresh greens, tomatoes, dark-green leafy vegetables, light-green vegetables, bananas, oranges, and apples. In take of pork, eggs, and the three fruits was directly related to income and education, which were inversely related to lung cancer risk. Case-control differences nevertheless persisted across income and education strata. By regression analysis, results were similar across duration categories of underground mining exposure. Nonsmokers were too few to permit evaluation of dietary associations in this group. The results provide further evidence that fruits and vegetables are protective against lung cancer but do not support the theory that β-carotene is specifically responsible for the effect.
In addition to protecting against lung cancer, fruits and vegetables may lengthen survival of lung cancer patients. (106). Analysis of records from the Hawaii Tumor Registry showed covariate- adjusted median survival times for women of 33,21,15 , and 18 month from the highest to the lowest quartiles of vegetable intake. There was also a significant trend for fruit intake and survival in women. High consumption of tomatoes or oranges signifcanly improved survival in men; broccoli and perhaps tomatoes were beneficial in women. No associations were beneficial in women. No associations ere found for consumption of specific micronutrients or of other carotene-rich foods.
To confirm findings of a cohort study in which an excess of lung cancer occurred among certain groups of meat industry workers, a nested case- control study of lung cancer in the meat industry was undertaken (107). It confirmed the existence of excess risk of lung cancer throughout the meat industry. Risk increased with duration of employment in the meat industry. The major risk factors for meat handlers compared to workers in non-meat industries were contact with raw meat for ≥5y, contact with raw meat in abattoirs, and contact with raw meat in supermarkets. However, workers having contact with raw meat in meat-packing plants and supermarkets in these departments who did not have direct contact with meat, suggesting that other occupational risk factors may be involved, such as exposure to fumes from heat-sealing plastic during wrapping.
