Expert Commentary

Cancer incidence and mortality rates decline, but not for poor Americans

Cancer incidence and mortality rates are on the decline in the U.S., but not for everyone. Socioeconomic disparities are widening.

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Cancer incidence and mortality rates are on the decline in the U.S., but not for everyone. Socioeconomic disparities are widening, especially for preventable cancers, according to new research published in CA: A Cancer Journal for Clinicians.

The study looks at data collected between 1930 and 2016 by three national cancer registries affiliated with the National Institutes of Health and the Centers for Disease Control and Prevention to analyze historical incidence trends for men and women and for specific types of cancer. The authors also used this data to estimate future incidence and mortality rates. Projections for the number of estimated new cases in 2019 are broken down for each of the 50 states by type of cancer.

The research finds that on the whole, cancer death rates are declining, and have been on the decline for the past 25 years. From 1991 to 2016, the overall cancer death rate dropped by a total of 27 percent – an estimated 2,629,200 fewer cancer deaths than if rates had remained at 1991 levels.

Rebecca Siegel, lead author of the paper and scientific director of surveillance research at the American Cancer Society said in a phone call with Journalist’s Resource that the decline can be attributed to reductions in smoking prevalence as well as improvements in early detection and treatment for some cancers, including breast, cervical and colorectal cancer.

Racial disparities in cancer mortality are also on the decline. The black-white disparity in cancer mortality overall, for men and women combined, declined from 279 cancer deaths among black people compared to 210.5 deaths among white people per 100,000 in 1993; in 2016 the death rates per 100,000 stood at 183.6 vs. 160.7. The authors explain that “This progress is largely due to the steep drop in smoking prevalence unique among black teens from the late 1970s through the early 1990s.”

But socioeconomic disparities are another story. Whereas prior to the mid-1980s, lower socioeconomic status was associated with lower cancer mortality, the trend has now flipped. “Notably, socioeconomic deprivation was associated with lower cancer mortality prior to the mid‐1980s because of the later development of effective treatment and the historically elevated risk of lung and colorectal cancers among individuals with high [socioeconomic status],” the authors write. However, between 2012 and 2016, the overall cancer death rate was about 20 percent higher for those who live in the poorest counties, compared with residents of the most affluent counties.

Colorectal, lung and cervical cancer are three types of cancer that have increased incidence and mortality rates among people who live in poor counties, according to the paper. Colorectal and lung cancer are tied to behavioral factors that increase cancer incidence, such as smoking and obesity. Cervical cancer is highly preventable and treatable, but only if patients have access to health care. As it stands, cervical cancer mortality for women in poor counties is twice that of women in affluent counties.

“Surprisingly, the socioeconomic disparity is widening,” Siegel said, “and it’s particularly large for cancers that are preventable, which highlights the opportunities that there are to use what we know now to prevent cancer, detect cancer and to treat it.”

Siegel said it is “somewhat ironic” that advances in cancer prevention, detection and treatment “actually create and widen these disparities, because these advances are much, much slower to disseminate among disadvantaged populations.”

She suggested that interventions to reduce these disparities might include increasing access to care for people of lower socioeconomic status. Research has shown that such interventions can work to reduce racial disparities. Siegel pointed to Delaware as an example of a state that has successfully reduced racial disparities in cancer incidence and mortality through increased access to screening and assistance from nurse navigators, who assist patients in medical decision-making and provide support for accessing care.

“Targeted interventions that reach these segments of the population that we’re talking about, it has been shown that they work,” Siegel said.

For journalists looking to cover this research from less-explored angles, Siegel suggested expanding on two of the paper’s findings.

“Almost 10 women per week in their twenties and thirties died from cervical cancer in 2016,” she said. Siegel suggested reporters might shed light on the stories of these women, many of whom are poor and have never received screening.

Siegel also suggested a story lead tying the opioid epidemic with a finding from the paper. Liver cancer death rates are increasing rapidly, she noted. Between 2010 and 2014 liver cancer incidence rates increased by 2.8 percent for men and 3.8 percent for women, according to a May 2018 study published in Cancer. Liver cancer is largely preventable through potentially modifiable factors such as diet, Siegel said, adding that one-third of liver cancer cases in the U.S. are tied to obesity. Additionally, one-fourth of cases are caused by hepatitis C virus infection. The virus is spread by blood, so it can be transmitted through used needles. Siegel predicted future increases in liver cancer rates due to recent spikes in hepatitis C incidence, which have been linked to the opioid epidemic and injection drug use.

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