Rebecca L. Siegel
The overall rate of cancer deaths in the U.S. has declined by 27% during the past 25 years, with approximately 2.6 million fewer cancer deaths reported between 1991 and 2016, according to data from Cancer Statistics 2019, American Cancer Society’s annual report on cancer rates and trends.
However, cancer remains the second leading cause of death in the U.S. after heart disease among men and women, and it was responsible for 22% of U.S. deaths in 2016.
Additionally, while racial disparities in cancer deaths are slowly narrowing, socioeconomic gaps are widening, with poorer counties facing increasingly imbalanced cancer death rates. This disproportionate burden is particularly pronounced among the most preventable cancers, such as lung and cervical cancer.
“These counties are low-hanging fruit for locally focused cancer control efforts, including increased access to basic health care and interventions for smoking cessation, healthy living and cancer screening programs,” Rebecca L. Siegel, MPH, director of surveillance research for American Cancer Society, and colleagues wrote in the report, published in CA: A Cancer Journal for Clinicians. “A broader application of existing cancer control knowledge with an emphasis on disadvantaged groups would undoubtedly accelerate progress against cancer.”
Siegel and colleagues acquired cancer incidence data through 2015 from the SEER program, the National Program of Cancer Registries and the North American Association of Central Cancer Registries. They compiled mortality data through 2016 from the National Center for Health Statistics.
Based on these data, the researchers projected that in 2019, there will be 1,762,450 new cancer cases and 606,880 cancer deaths in the U.S.
The cancer death rate reached its peak in 1991, with 215.1 deaths per 100,000 population, but dropped steadily by about 1.5% per year to 156 per 100,000 population in 2016.
The 27% total reduction translates to 1,804,000 cancer deaths averted among men and 825,200 averted among women. From 2007 to 2016, cancer death rates declined annually by 1.4% in women and 1.8% in men.
Lifestyle modifications, advances in detection
The authors attributed the reduction in cancer mortality rates primarily to decreases in smoking and innovations in early detection and treatment. These factors are apparent in the decreases for the four major cancers: lung, breast, prostate and colorectal.
The lung cancer death rate decreased by 48% from 1990 to 2016 among men and by 23% from 2002 to 2016 among women, with the declines gaining momentum in recent years. The mortality rate for female breast cancer declined by 40% between 1989 and 2016, and the mortality rate for prostate cancer decreased by 51% between 1993 and 2016. A 53% decrease in colorectal cancer occurred from 1970 to 2016.
Conversely, death rates for some less common cancers have increased over the past 2 decades. Liver cancer mortality rates increased 2.6% annually among women and 1.2% among men between 2012 and 2016, as did the annual rates of pancreatic cancer among men (0.3%) and endometrial cancer (2.1%).
Mortality rates also increased for brain and other nervous system cancers, soft tissue (including heart) cancer, and cancer within the oral cavity and pharynx linked to HPV.
According to the authors, improvements in survival for lung and pancreatic cancers have been slow because more than half of these cases are diagnosed at a late stage.
Between 2006 and 2015, the overall cancer rate remained unchanged in women and decreased by roughly 2% per year in men. The decrease among men was fueled by accelerated declines of roughly 3% per year for lung and colorectal cancers and 7% per year for prostate cancer, which researchers attributed to decreased PSA testing.
Among women, declines in lung cancer incidence have continued, but have slowed in recent years for colorectal cancer, whereas the rate of breast cancer incidence has increased by 0.4% per year.
Incidence rates continue to rise for melanoma, as well as for cancers of the liver, thyroid, uterine corpus (endometrium) and pancreas.
The incidence of liver cancer is increasing faster than that of any other cancer in both sexes. However, researchers noted that most (71%) of these cases in the U.S. may be preventable, because most of their risk factors — obesity, excess alcohol consumption, cigarette smoking, and hepatitis B and C viruses — are modifiable.
A more balanced approach
Although racial gaps in cancer mortality are gradually shrinking, socioeconomic disparities are worsening, particularly in the most preventable cancers.
Compared with the wealthiest counties in the U.S., cancer death rates in the poorest counties were twice as high for cervical cancer and 40% higher for male lung and liver cancers from 2012 to 2016.
Conversely, socioeconomic disparities in mortality rates for cancers that are less preventable or treatable — such as leukemia, non-Hodgkin lymphoma, pancreatic and ovarian cancers — are small or nonexistent.
Before the 1980s, socioeconomic deprivation was linked to lower rates of cancer death. The shift in these rates is most pronounced for colorectal cancer death; in the 1970s, men in the poorest counties had roughly 20% lower rates than those in the wealthiest counties. Now, men in poorer counties have a 35% higher colorectal cancer mortality rate.
“This reversal reflects changes in dietary and smoking patterns that influence colorectal cancer risk, as well as the slower dissemination of screening and treatment advances among disadvantaged populations,” the researchers wrote. “A similar crossover occurred earlier for male lung cancer mortality because historically, men of higher socioeconomic status were much more likely to smoke.”
Noting that some states include both the most affluent and poorest counties, researchers indicated there may be opportunities to more equitably implement effective cancer prevention, early detection and treatment strategies.
“A broader application of existing cancer control knowledge with an emphasis on disadvantaged groups would undoubtedly accelerate progress against cancer,” they wrote. – by Jen Byrne
Disclosures: All authors are employed by American Cancer Society, which receives grants from private and corporate foundations, including foundations associated with companies in the health care sector for research outside of the submitted work. The authors are not funded by or key personnel for any of these grants, and their salaries are funded solely through American Cancer Society funds.