A new study by government researchers has found a remarkable flip-flop in cancer mortality among American men over the last half-century. While in 1950 cancer deaths were nearly 50 percent more common among the wealthy than the poor, by 1998 they were 19 percent more common in the lowest income groups than in the highest. Most, but not all, of the shift is due to a transfer in lung cancer deaths from the rich to the poor, the researchers said.
"The trends for total cancer mortality and lung cancer tend to be similar, and it is consistent with the time trend in smoking," said study leader Gopal Singh, a statistician at the National Cancer Institute.The bright spot is that deaths from lung tumors, and from cancer overall, have been declining lately. This year, lung cancer will claim an estimated 150,000 lives, according to the American Cancer Society. That's down from 154,000 in 1998.
Singh's findings appear in today's issue of the Journal of the National Cancer Institute. He and his colleagues plotted cancer death rates in men against the social and economic status of counties, divided into five brackets from poorest to richest. An area's socioeconomic status was a reflection of its residents' average household income, level of education, occupation, and several other factors.
In a second study, also published in the cancer institute's journal, Singh's group looked for effects of class on death rates from lung and colorectal cancer -- the country's two leading cancer killers -- in both men and women.
In 1950, men in higher classes had greater rates of death from lung cancer than those in society's poorer sectors. But they traded places in the 1970s and beyond, and by 1998 lung cancer deaths were 56 percent more common among young men in the poorest bracket than for those in the wealthiest fifth. They were 38 percent higher among men over 65 in the bottom rung compared with the top.
Lung cancer deaths in women over age 65 jumped roughly eight-fold between 1950 and 1998, Singh's group found. The highest rates were seen in the wealthier groups. Singh said that probably reflects a lag in the impact of higher smoking rates among wealthier women 20 to 30 years ago.
Although changes in smoking habits account for most of the shift in lung cancer death rates, they're not the whole story. "Even among nonsmokers, lung cancer mortality tends to be higher among men and women" in disadvantaged groups, Singh said, so some other factors seem to be at play.
The picture was less clear for colorectal cancer. Deaths from the disease increased among poor men over the decades but fell among wealthier men and among women of all social and income groups.
The researchers said it's unlikely that access to care makes much difference in survival from lung cancer, which has a generally grim prognosis. But it might be more influential in colorectal cancer, for which an early diagnosis is critical. "The screening is part of the health services domain," Singh said.
People in wealthier communities, who presumably have better access to colorectal cancer screening, are more likely to survive the disease. That trend holds even after accounting for the stage of their tumors at diagnosis, suggesting that the poor may have inferior cancer -- or general -- medical care.
These gaps will likely persist and even widen, Singh said, if current rich-poor differences in smoking and exercise habits, diet, access to cancer screening, and patterns of diseases like diabetes stay strong.
Norman Anderson, a professor at the Harvard School of Public Health in Boston, said the new findings aren't surprising.
"We have known for some time that lower socioeconomic status, whether measured on an individual level or an area level, is related to a wide array of adverse health outcomes." However, he said, it's one of the few studies to look at how these relationships change with time.
Anderson, a former associate director of the National Institutes of Health, said the results should prompt researchers and policy makers to look beyond the plight of the poor person to the health of the community in which he or she lives. Places, it appears, have a real and powerful effect on health.
Scientists have found, for example, that people of means who choose to live in disadvantaged neighborhoods have higher rates of early death than their same-class peers living in a wealthy area.
"We have to think about what is happening in these different socioeconomic neighborhoods," Anderson said. "We have to move upstream to the more fundamental causes of things like smoking and cancer."
Dr. Alvin Tarlov, executive director of the Texas Institute for Society and Population Health at Rice University in Houston, called the new findings "astonishing." And he agreed with Anderson that individual behavior can explain only a fraction of the effects on health of the community.
"The steep hierarchical social structures that are characteristic of American life are a serious risk factor for ill health," Tarlov said. "The penalty is not only for the people at the bottom, but it appears also to penalize the people at the top. There is something pervasive about the implications," he said.
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