ancer statistics are usually not based on an accurate count of cases but on estimations derived from various sources. There is no national cancer registry that counts every cancer diagnosed each year. The American Cancer Society publishes annual estimates based on a compilation of several local tumor registries and extrapolates these to the US population. Like all statistics, cancer numbers can be misused and misunderstood. For instance, the state of California made cancer a reportable disease in 1985, so they have reasonably good statistics. Marin county, an affluent ocean bordering county, has the highest incidence of breast cancer in the state, Fresno county, an inland agricultural county, one of the lowest.
Why is this? Maybe Marin county is deficient in agricultural chemicals in the environment and has too much fresh sea air. Are they too close to a nuclear power plant? Is there something in the water? Too much time spent in hot tubs and health food stores? Should you avoid Marin county? The explanation is not quite so exotic. The highest incidence of cancer occurs in older white women, women with fewer pregnancies, and those who have delayed their pregnancies. Marin county has a population of affluent older white women. Fresno county has a large population of young Hispanic multiparous women. Hispanics have a lower incidence of all cancers compared to white women.
Whenever you hear cancer statistics being quoted, beware. The numbers may be only estimates and will have been interpreted to support the point of view of whoever is quoting them. For example the incidence of breast cancer has increased over the past several years. Is there an epidemic of breast cancer? Most of this increase can be explained by the increased use of mammography screening. Mo ...