Geographic Patterns of Large Bowel Cancer in the United States

Our plain-English summary of Geographic Patterns of Large Bowel Cancer in the United States, by W.J. Blot, J.F. Fraumeni JR, B.J. Stone, et al (1976).

The study

• Authors: W.J. Blot, J.F. Fraumeni JR, B.J. Stone, F.W. McKay
• Published: Journal of the National Cancer Institute, Volume 57 No6. December 1976
• Type of article: Journal article
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This study examined deaths from colon and rectal cancer in the 3,056 counties of the contiguous United States during 1950-69. The authors compared age-adjusted county death rates, by sex and race (white and nonwhite), with 1960 census data on income, schooling, population size and density, and ethnic background. Alcohol sales data were available for 217 counties in six States. The study did not examine asbestos exposure. Asbestos appears only in the discussion, where the authors noted, citing earlier work, that it was then the only agent linked to intestinal cancer. Among whites, colon cancer death rates were higher in the Northeast than in the Southeast, and higher in heavily populated and higher-income counties. They were also higher in counties with more people of Irish, Czechoslovak or German stock. Regional differences persisted after these factors were taken into account. Alcohol sales showed no consistent relationship with rectal cancer. Patterns among nonwhites resembled those among whites. The authors concluded that urban, socioeconomic and ethnic factors only partly explained the higher rates in the North.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Geographic (ecological) correlation study comparing county-level death rates with county-level census and alcohol-sales data, using weighted regression
• Who was studied: The 3,056 counties of the contiguous United States, with death rates for 1950-69 by sex and race (white and nonwhite). Nonwhites were analyzed only in the 1,043 counties with at least 2,000 nonwhite residents.
• Exposure: County characteristics from the 1960 census: median family income, median school years, population size and density, percent urban, percent rural farm, percent nonwhite, and percent of foreign stock for 13 ethnic groups. Also alcoholic beverage sales (1970-74) for 217 counties in six States. Asbestos exposure was not studied.
• Main results:
  • Among whites, the sharpest regional contrast in colon cancer death rates was between the Northeast and the Southeast. 98% of Northeastern county rates exceeded the Southeastern median, and only 4% of Southeastern counties equaled or exceeded the Northeastern median.
  • Colon cancer death rates among white males and females were elevated in heavily populated counties.
  • Colon cancer death rates among whites rose with county income level. This was consistent across all areas except for females in the Midwest and North Central regions.
  • Among whites, substantial regional differences in colon cancer death rates persisted after urban and socioeconomic factors were taken into account.
  • Among whites, colon cancer death rates were higher in females than in males in 63% of the 2,662 counties with populations under 75,000. In counties with populations over 75,000, rates were higher in females in only 42% of counties.
  • Among whites, the largest increases in colon cancer death rates were in counties with a higher percentage of people of Irish stock. Rates were also higher with Czechoslovak or German descent, and low in areas with many residents of Scandinavian or Mexican and South American descent.
  • Among whites, rectal cancer death rates were highest in the Northeast and lowest in the Southeast. The male-to-female death rate ratio rose with increasing county population size.
  • No consistent relationship was found between rectal cancer death rates (adjusted for demographic factors) and alcohol tax revenues in the six States studied. County beer sales showed only weakly positive associations with rectal cancer death rates in males.
  • Among nonwhites, colon and rectal cancer patterns resembled those of whites. Rates were generally higher in the North than in the South, and higher in counties with large populations and elevated income levels.
  • The study did not examine asbestos. In discussing occupational factors, the authors noted, citing another study, that asbestos was to date the only agent linked to intestinal cancer.
• The authors' conclusion: The authors concluded that urban, socioeconomic and ethnic factors were each linked to large bowel cancer, but only partly explained its predominance in the Northern United States. They found the variation in the limited regional diet data and county alcohol sales data, alongside bowel cancer rates, not impressive.
• Limitations the authors state:
  • The alcohol sales data were not comparable from State to State. They only measured relative alcohol use among counties within each State.
  • Nonwhite populations in many counties were too small to give meaningful rates, so the nonwhite analysis was limited to 1,043 counties.
  • County-level data on diet were not available for comparison with county death rates.
  • Tumor location within the colon was unspecified on most death certificates.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Colorectal Cancer.

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