The last half-century has also seen a sharp decline in death rates from cervical cancer and gastric cancer in the United States. The decrease in cervical cancer is directly attributable to widespread use of the Papanicolaou (PAP) smear test for early detection of this tumor and its precursor lesions. The deployment of the human papillomavirus (HPV) vaccine may nearly eliminate this cancer in coming years. The cause of the decline in death rates for cancers of the stomach is obscure; it may be related to decreasing exposure to unknown dietary carcinogens.
Environmental exposures appear to be the dominant risk factors for many common cancers, suggesting that a high fraction of cancers are potentially preventable. This notion is supported by the geographic variation in death rates from specific forms of cancer, which is thought to stem mainly from differences in environmental exposures. For instance, death rates from breast cancer are about four to five times higher in the United States and Europe than in Japan. Conversely, the death rate for stomach carcinoma in men and women is about seven times higher in Japan than in the United States. Liver cell carcinoma is relatively infrequent in the United States but is the most lethal cancer among many African populations. Nearly all the evidence indicates that these geographic differences have environmental rather than genetic origins. For example, Nisei (secondgeneration Japanese living in the United States) have mortality rates for certain forms of cancer that are intermediate between those in natives of Japan and in Americans who have lived in the United States for many generations. The two rates come closer with each passing generation.
http://ebooksmedicine.net
Men 314,290 Women 281,400
There is no paucity of environmental factors that con-with a modestly increased risk for developing many tribute to cancer. They lurk in the ambient environment, in different cancers. the workplace, in food, and in personal practices. They can • Smoking. Smoking, particularly of cigarettes, has been be as universal as sunlight or be largely restricted to urban implicated in cancer of the mouth, pharynx, larynx, settings (e.g., asbestos) or particular occupations ( esophagus, pancreas, bladder, and, most significantly, 6.2 ). The most important environmental exposures linked the lung, as 90% of lung cancer deaths are related to to cancer include the following: smoking.
• Diet. Certain features of diet have been implicated as • Alcohol consumption. Alcohol abuse is an independent predisposing influences. More broadly, obesity, cur-risk factor for cancers of the oropharynx, larynx, esophrently epidemic in the United States, is associated agus, and (due to alcoholic cirrhosis) liver. Moreover,
Table 6.2 Occupational Cancers
Human Cancers for Agents or Groups Which Reasonable of Agents Evidence Is Available Typical Use or Occurrence
ArsenicandarsenicLungcarcinoma,skincarcinomaBy-productofmetalsmelting;componentofalloys,electricalandsemiconductordevices,compounds medicationsandherbicides,fungicides,andanimaldips
BenzeneAcutemyeloidleukemiaPrincipalcomponentoflightoil;despiteknownrisk,manyapplicationsexistinprintingandlithography,paint,rubber,drycleaning,adhesivesandcoatings,anddetergents;formerlywidelyusedassolventandfumigant
BerylliumandberylliumLungcarcinomaMissilefuelandspacevehicles;hardenerforlightweightmetalalloys,particularlyincompounds
ChromiumcompoundsLungcarcinomaComponentofmetalalloys,paints,pigments,andpreservatives
NickelcompoundsLungandoropharyngealNickelplating;componentofferrousalloys,ceramics,andbatteries;by-productofcarcinomastainless-steelarcwelding
ModifiedfromStellmanJM,StellmanSD:Cancerandtheworkplace,CA Cancer J Clin 46:70–92,1996,withpermissionfromLippincottWilliams&Wilkins.