Cancer Mortality Continues to Spiral Downward in the US

Pam Harrison

January 08, 2019

Mortality rates from the most common cancers continue to decline across the United States, with several notable exceptions, including liver cancer in men and especially in women, and also uterine cancer in women. These findings come from the latest American Cancer Society annual report on cancer rates and trends, "Cancer Statistics 2019."

The report was published online January 8 in CA: A Cancer Journal for Clinicians.

Overall cancer death rates dropped by 27% in the 25 years from 1991 to 2016, Rebecca Siegel, MPH, scientific director of surveillance research, American Cancer Society, Atlanta, Georgia, and colleagues report.

There are approximately 2,629,200 fewer deaths from cancer now than would have been expected had death rates remained at their peak, the researchers observe.

The number of averted deaths is greater for men than for women because the total decline in cancer mortality has been steeper for men than for women (34% vs 24%), they point out.

People living in the poorest counties of the country are experiencing a disproportionate burden of the most preventable cancers, including cervical, lung, liver, and colorectal cancer (CRC). The mortality rates for these cancers are considerably higher than they are for residents in more affluent counties, the authors note.

Nearly 1700 Deaths Each Day

Despite the downward trend for cancer mortality, the disease continues to kill.

The authors estimate that in 2019, 606,880 US residents will die from cancer — corresponding to nearly 1700 deaths per day.

"The greatest number of deaths are from cancers of the lung, prostate, and colorectum in men and the lung, breast, and colorectum in women," Siegel and colleagues note.

One quarter of all cancer deaths are from lung cancer, they add.

That said, the incidence of lung cancer continues to decline twice as quickly among men than among women, a reflection of an uptick in smoking by women in some birth cohorts.

The death rate for lung cancer dropped by 48% from 1990 to 2016 among men and by 23% from 2002 to 2016 among women. The decline in lung cancer deaths accelerated among both sexes in recent years.

For breast cancer, death rates dropped by 40% from 1989 to 2016. Mortality for prostate cancer declined by 51% from 1993 to 2016.

Death from CRC also dropped by a similar percentage, at 53%, although the trajectory of the decline in CRC deaths was longer than it was for prostate cancer, from 1970 to 2016.

Overall, the incidence of cancer during the past decade has declined by approximately 2% per year in men; for women, the incidence rate has remained relatively stable during the past few decades.

Liver Cancer Rates Are Increasing

In contrast to overall cancer trends, rates of liver cancer are increasing faster than for any other cancer in both men and women, as has been reported previously.

This is disturbing, the study authors suggest, because risk factors for liver cancer, which include obesity, excess alcohol consumption, smoking, and hepatitis B and C infection, are all potentially modifiable. As such, many cases of liver cancer could be prevented, they argue.

Some 75% of individuals affected by liver cancer are baby boomers, the researchers note.

One-time hepatitis C screening has been recommended for this age group, but in 2015, only a small percentage of baby boomers had been screened for the infection.

The problem is further compounded by the opioid epidemic — a threefold spike in hepatitis C infection was reported to the Centers for Disease Control and Prevention from 2010 to 2016, researchers add.

High Survival Rates for Common Cancers

For all stages of cancer combined, "survival is highest for prostate cancer (98%), melanoma of the skin (92%), and female breast cancer (90%)," Siegel and colleagues note.

In contrast, 5-year survival rates are lowest for cancer of the pancreas, at 9%; liver cancer, at 18%; and cancer of the esophagus and lung, both at 19%.

For children and adolescents, overall cancer incidence rates have been increasing very slightly, by 0.7% per year, since 1975.

However, death from cancer in those age groups has been on the decline for many decades, to the point where now, children and adolescents are more than 60% less likely to die of their cancer than they were in 1970.

"Much of this progress reflects the dramatic 78% decline in leukemia mortality, from 2.7 per 100,000 children and adolescents in 1970 to 0.6 in 2016," the researchers observe.

Racial Differences Narrowing, but Socioeconomic Inequalities Loom

Five-year relative survival rates for all cancers diagnosed from 2008 to 2014 were roughly equal between whites, at 67%, and blacks, at 62%.

However, "after adjusting for sex, age, and stage at diagnosis, the relative risk of death after a cancer diagnosis is 33% higher in black patients than in white patients," the researchers observe.

The discrepancy in cancer death rates is even greater for American Indians and Alaska Natives, who are 51% more likely than white patients to die of their disease.

Although the racial gap in cancer mortality rates is slowly narrowing, socioeconomic inequalities are widening. This gap is characterized by significantly higher cancer mortality rates among the poor.

For example, the rate of mortality from cervical cancer among women living in poor counties is twice that among women living in affluent counties. Mortality from both lung and liver cancer among men living in poor counties is more than 40% higher than it is for men living in wealthier counties.

In the early 1970s, mortality rates from CRC among men in the poorest counties were about 20% lower than they were for men living in wealthy counties; now, rates are 35% higher for men living in the poorest counties, the investigators point out.

Indeed, it has been estimated that approximately one third of cancer-related deaths in residents aged 25 to 74 years could be avoided if socioeconomic disparities were eliminated.

The authors point out that residents living in the poorest counties are far more likely to engage in the kind of behaviors that give rise to cancer. For these persons, rates of smoking and obesity are twice those of people living in the wealthiest counties.

This is reflected by geographic variations in the incidence of cancer. For example, lung cancer rates in Kentucky are about 3.5 times higher than they are in Utah, and smoking rates are the highest in Kentucky and the lowest in Utah, the investigators note.

"A broader application of existing cancer control knowledge with an emphasis on disadvantaged groups would undoubtedly accelerate progress against cancer," Siegel and colleagues suggest.

The authors have disclosed no relevant financial relationships.

CA Cancer J Clin. Published online January 8, 2019. Full text

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