Keynote lecture. Etiologic insights from cancer mapping

Area of Science:

• Epidemiology and Biostatistics
• Environmental Health
• Public Health

Background:

• The U.S. National Cancer Institute's epidemiology program initiated systematic efforts in the 1970s to detect cancer clusters.
• Analysis focused on county-level mortality patterns, balancing population size for data reliability and homogeneity.
• Early mapping revealed diverse geographic patterns in cancer mortality rates from 1950-1969.

Purpose of the Study:

• To describe how geographic patterns identified potential causes of various cancers.
• To explore the progression from descriptive and correlational studies to analytical investigations.
• To highlight the utility of small-area cancer mapping for identifying environmental and lifestyle determinants.

Main Methods:

• Systematic analysis of county-level cancer mortality data.
• Computer-generated color-coded maps to visualize geographic patterns.
• Progression of studies: descriptive, correlational, and analytical to investigate elevated risks.

Main Results:

• High lung cancer rates in men linked to asbestos exposure in shipyards.
• Elevated oral cancer rates in rural southern women associated with smokeless tobacco use.
• Updated maps (1970-1980) showed some rate uniformity but identified new high-risk areas for lung, oral cancers, and non-Hodgkin's lymphoma, potentially linked to smoking and agricultural exposures.

Conclusions:

• Small-area cancer mapping is an effective strategy for generating and pursuing leads on cancer determinants.
• The mapping approach has successfully stimulated and targeted research into cancer origins and prevention globally.
• Environmental and lifestyle factors significantly contribute to observed geographic variations in cancer mortality.