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11. What is known about the occurrence of stomach cancer in different countries?

Although a large proportion of cancer deaths in the United States arise from stomach cancer, it is a decreasing cause of death. This change in mortality results from a falling incidence, not from any change in prognosis, and there is no assignable reason for the decrease in incidence.

Geographical differentials for this type of cancer are very striking. Roughly speaking, countries in higher latitudes seem to have a higher stomach cancer mortality. Especially high rates are noted in Japan, where stomach cancer mortality is apparently increasing rather than decreasing. In Latin America, on the contrary, stomach cancer seems to be relatively uncommon.

Epidemiological leads are few. In England and Wales and Denmark stomach cancer incidence is greatest in the lowest socioeconomic groups, least in the highest. In the United States incidence is also inversely related to income level. There is an unusually high incidence of stomach cancer in some occupation groups in England and Wales. A relation of stomach cancer with soil types and diet has also been suggested for some areas in Holland. (Source: Haenszel, W."Variation in Incidence of and Mortality From Stomach Cancer, With Particular Reference to the United States," Journal National Cancer Institute, vol. 21, pp. 213-262, 1958.)

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Increased frequency in females noted also

Source.-Dunham, L. J., and Dorn, H. F., "Techniques in the Geographic Pathology of Cancer. 1955. (Transactions of the 5th Meeting of the International Society of Geographical Path ogy.)

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Schweiz, Z. Path. Bakt. 18: 472.

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12. What is known about the occurrence of lung cancer in different countries?

Now the leading cause of cancer death for males in this country, cancer of the lung, pleura, and bronchi has been increasing rapidly both in incidence and mortality. Increases, in some instances of even greater magnitude, have been reported in many other countries. The level of mortality reached in England and Wales is especially striking. Prognosis for this type of cancer remains very poor, despite improvements in surgical techniques.

Epidemiological investigations of lung cancer have proved very fruitful. Excess risks have been shown to be associated particularly with cigarette smoking, urban residence, and certain occupations, such as processing of chromate ores. These have been demonstrated by data from a number of countries. Similarly, it has been shown that lung cancer incidence is greatest in the lowest socioeconomic groups in England and Wales, Denmark, and the United States. (Sources: Dorn, H. F., and Cutler, S. J., op. cit. Stocks, P., “Epidemiological Studies of Cancer of Various Organs," WHO; Subcommittee on Cancer Statistics, Nov. 1 (1957).)

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13. What is known about the occurrence of breast cancer in different countries?

In this country, the main site of cancer in females is the breast, and during the last 25 or 30 years there has been little change either in incidence or prognosis. A similar situation prevails in many other countries, including Western Europe, Canada, and Australia. A few areas, however, appear to have a much lower incidence-Japan and southeast Asia in particular.

In England and Wales, and Denmark, breast cancer occurs relatively more frequently among women in the higher socioeconomic groups. In this country, a higher than average incidence is also found in high income groups. Studies in England and Wales show that during the childbearing years married women have a lower death rate for breast cancer than unmarried and that married women with children have a lower mortality than those without children. This was also shown in Australia and France. (Sources: Dorn, H. F., and Cutler, S. J., op. cit. Stocks, P., op. cit.)

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