Cancer incidence rates

Cancer incidences, the number of new cases occurring annually, increased by 85% from 1950 to 2001. In 1950, one in four Americans would be 

Cancer incidence rates are reported annually by the International Agency for Research on Cancer (IARC). In 2002, the latest year for which statistics are available, the four most prevalent cancers worldwide are 

For all these cancers, incidence rates are highest in the industrially developed areas of the world, where people are exposed to higher levels of carcinogenic chemicals. In each case, those living in areas with lower incidences for a particular cancer demonstrate increased rates when they migrate to areas with higher incidences, further demonstrating the cancer causative effects of environmental and occupational exposures to toxic chemicals. 

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Table 5.1 provides 2005 statistics from the American Cancer Society on new cases, not deaths, for the cancers that occur most frequently. Cancer incidence rates vary by race and gender in about the same way that death rates vary. 

Isacson et al. (1985) examined the association between cancer incidence and indices of water contamination in an ecological study conducted in the central United States. Cancer incidence rates in towns with populations between 1000 and 10 000 were compared by level of volatile organic compounds and metals in the drmking-water. Among men, significant associations between the level of 1,2-dichloroethane (>0.1 ppm) and colon p = 0.009) and rectal cancer p = 0.02) were observed. The authors stated that 1,2-dichloroethane might be an indicator for other types of contamination rather than a causal agent. 

In a cohort study of workers in two Danish chemical plants (Lynge, 1985), potential exposure to 2,4,5-trichlorophenol occurred between 1951 and 1959, when small amounts were produced or purchased to make 2,4,5-T. No overall increase in cancer incidence rate was observed, but there were significantly increased risks of soft-tissue sarcoma and lung cancer in certain subcohorts. [The Working Group noted that 2,4-dichlorophenol is an intermediate in the production of 2,4-D, which was produced by the larger of the two plants.]... 

Drinking water quality concerns range from (1) infectious disease risks that are large, obvious, and quantifiable (2) acute or chronic chemical hazards such as those from arsenic or lead that are infrequent but potentially identifiable in cause and effect when they occur (3) postulated carcinogenic risks from radionuclides or certain organic chemicals that are largely undetectable and empirically unquantifiable and usually small in magnitude relative to overall cancer incidence rates. 

However, this option presents some difficulties for radionuclides, because studies of radiation effects in human populations have focused on cancer fatalities as the measure of response and probability coefficients for radiation-induced cancer incidence have not yet been developed by ICRP or NCRP for use in radiation protection. Probabilities of cancer incidence in the Japanese atomic-bomb survivors have been obtained in recent studies (see Section 3.2.3.2), but probability coefficients for cancer incidence appropriate for use in radiation protection would need to take into account available data on cancer incidence rates from all causes in human populations of concern, which may not be as reliable as data on cancer fatalities. Thus, in effect, if incidence were used as the measure of stochastic response for radionuclides, the most technically defensible database on radiation effects in human populations available at the present time (the data on fatalities in the Japanese atomic-bomb survivors) would be given less weight in classifying waste. 

Mills, P.K. (1998). Correlation analysis of pesticide use data and cancer incidence rates in California counties. Arch. Environ. Health, 53(6) 410 113. 

The observation that breast cancer incidence rates vary 10-fold between countries suggests that environmental factors play an important role in the etiology of breast cancer. Perhaps the most compelling evidence is derived from studies of Asian women who migrated from Japan to the San Francisco Bay area. Although the incidence of breast cancer in Asian women is quite low (about 97 cases per 100,000 women), the incidence of breast cancer in Asian women who were bom in the United States, or who migrated from Asia to the United States, gradually increases to equal that of the white population in the same area. 

Although it is difficult to compare trends because of large year-to-year variations in colorectal cancer incidence rates in minority population groups, downward trends in colorectal cancer incidence appear to be greater for whites, African-Americans, Asian/Paciflc Islanders, and American Indian/Alaskan Native Americans than for Hispanics. Trends for incidence and mortality rates among white and African-American males and females in the United States can be compared in Fig. 127-1. 

Hamilton et al. (1989) studied 3503 children who underwent a diagnostic scan. No excess of thyroid cancer was detected when compared to population-based thyroid cancer incidence rates. Other studies also conclude that there is no evidence of a relationship between a low-activity diagnostic scan with and thyroid cancers or benign nodules (Hall et al., 1996b Hahn et al, 2001). 

The Committee also concluded that this comparison of gross carrageenan consumption in the USA with national breast cancer incidence rates cannot prove causation. No adjustment was made for non-food consumption, and consumption was analysed as though it was distributed equally throughout the population. Similarly, no adjustments were made for possible relationships between the 13 gums studied and any of the acknowledged risk factors for mammary carcinoma. 

Cancers caused by ionizing radiation occur several years after the exposure has taken place. They do not differ in their chnical appearance from cancers that are caused by other factors. A radiation-induced cancer cannot be recognized as such, and it is only by means of epidemiological studies that increases in the spontaneous cancer incidence rates of irradiated groups can be detected. Ionizing radiation is the carcinogen that has been most intensely studied. 

Fig. 7.4. Lifetime excess risk at 1 Sv organ dose in dependence on age at exposure for those cancer sites attributing most to the total excess lifetime risk according to BEIR VII risk models and German life tables and German cancer incidence rates...

Fig. C-18. Age-specific cancer incidence rates in the United States by sex.

Introduction 434 Cancer Incidence Rates 434 Chemical Carcinogens 435 Mechanisms of Carcinogenesis 439 Single Chemical Carcinogens 444... 

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