Credit: Rhoda Baer
Results of a large study suggest certain malignanices are more concentrated in areas with high levels of poverty, while other cancer types arise more often in wealthy regions.
The research, conducted using data from nearly 3 million US cancer cases, also indicated that areas with higher poverty levels tended to have a lower cancer incidence but higher mortality rate than areas with lower poverty levels.
Researchers reported these findings in the journal Cancer.
Francis Boscoe, PhD, of the New York State Cancer Registry in Albany, and his colleagues conducted this research to evaluate the role of socioeconomics in cancer incidence and mortality.
So the team compared individuals living in areas with the highest poverty levels to those living in areas with the lowest poverty levels.
The researchers collected information on nearly 3 million cancer cases diagnosed between 2005 and 2009 in16 states, plus Los Angeles (an area covering 42% of the US population). Cases were divided into 1 of 4 groupings based on the poverty rate of the residential census tract at the time of diagnosis.
For all malignancies combined, there was a negligible association between cancer incidence and poverty. However, 32 of 39 cancer types showed a significant association with poverty.
Fourteen cancers were positively associated with poverty, and 18 were negatively associated. Myeloma, Hodgkin lymphoma, and non-Hodgkin lymphoma (NHL) were among the negatively associated malignancies.
The cancers most significantly associated with higher poverty levels were Kaposi sarcoma and cancers of the larynx, cervix, penis, and liver. The cancers most significantly associated with lower poverty levels were melanoma, thyroid cancer, other non-epithelial skin cancers, and testis cancer.
Overall, male malignancy rates were more sensitive to poverty level than female rates. And, in general, the race-specific cancer incidence rates differed, but the poverty gradients were similar.
For example, there was a roughly 20-fold difference in rates of melanoma between white and black individuals, but the relationship between poverty and incidence remained regardless of race.
This was not true for NHL, however. Among black individuals, the incidence of NHL increased as the poverty level increased. But among white individuals, the incidence of NHL decreased as the poverty level increased.
The researchers pointed out that—for all cancer sites, races, and sexes combined—the difference in risk between the greatest and lowest poverty category was less than 2%.
“At first glance, the effects seem to cancel one another out,” Dr Boscoe said. “But the cancers more associated with poverty have lower incidence and higher mortality, and those associated with wealth have higher incidence and lower mortality. When it comes to cancer, the poor are more likely to die of the disease, while the affluent are more likely to die with the disease.”
Dr Boscoe noted that recent gains in technology have made it much easier to link patient addresses with neighborhood characteristics, therefore making it possible to incorporate socioeconomic status into cancer surveillance.
“Our hope is that our paper will illustrate the value and necessity of doing this routinely in the future,” he concluded.
