Researchers from the American Cancer Society identified trends in disparities and outcomes for cancer over the last few decades in an effort to highlight the need for better quality care for all individuals with cancer, according to a report published in CA: A Cancer Journal for Clinicians.
The data served as a prelude to framing of a national cancer control plan, or blueprint, for the American Cancer Society’s goal of reducing cancer mortality by 2035.
Rebecca L. Siegel
“Many more cancer deaths could be prevented through wider adoption of known cancer preventive behaviors and interventions and broader access to high-quality cancer care,” Rebecca L. Siegel, MPH, scientific director of surveillance information at the American Cancer Society, and colleagues wrote. “There are vast opportunities to reduce the cancer burden today, in the absence of new technologies or treatment, by expanding delivery of currently established evidence-based care to all Americans.”
The report is the first of a series of published articles on cancer control by the American Cancer Society that will highlight successes and challenges in cancer control and oncology, while identifying ways to better control cancer.
Overall cancer mortality has steadily decreased since 1991 due to declining death rates for lung, colorectal, breast and prostate cancers — cancers that account for almost half of all cancer deaths.
The mortality rate for lung, colorectal, breast and prostate cancers combined decreased 36% between 1991 and 2015 compared with 14% for all other cancers combined during the same period.
Researchers attributed decreased mortality rates to improved cancer prevention, screening and early detection, and cancer treatments.
However, trends in mortality across individual cancers indicated both opportunities and challenges in cancer control.
These trends include:
Lung cancer has remained the leading cause of cancer death in American men and women. Still, smoking prevalence dropped among men from 55% in 1955 to 17% in 2015, and among women from 35% in 1965 to 14% in 2015. The decrease in smoking has remained the biggest driver in the 26% decrease in cancer death rates; however, tobacco use is still the leading cause of cancer in the U.S. and accounts for approximately 19% of all cancers diagnosed and 29% of all cancer deaths reported in 2014.
Gastric cancer has not been a leading cause of mortality among men and women since 1930 — the age-adjusted death rate per 100,000 decreased from 46 in 1930 to four in 2015 among men and from 35 in 1930 to two in 2015 among women. Researchers attributed this decline to public health measures such as improved hygiene.
Uterine corpus and cervix cancer also represented a leading cause of cancer mortality among women in 1930, with a combined mortality rate of 36 per 100,000. Researchers attributed progress against cervical cancer to development and widespread use of the Pap test. The HPV vaccine and cervical screenings have created an opportunity to eliminate cervical cancer as a major cause of morbidity and mortality; however, vaccine uptake has remained low at 47.6% in the U.S. in 2016.
Liver and intrahepatic bile duct cancer mortality rates rose from 2.8 per 100,000 in 1975 to 6.5 per 100,000 in 2015. Alcohol use has remained an important cause of liver cancer, but researchers attributed the increase in liver-related deaths over time to prevalent hepatitis C virus infection throughout the 1960s and 1980s, as well as increased obesity rates.
Non-Hodgkin lymphoma mortality rates increased from 5.6 per 100,000 in 1975 to 8.9 per 100,000 in1997 as a result of the HIV epidemic. The incidence rate decreased to 5.7 per 100,000 in 2015 after the introduction of antiretroviral therapy and improved treatments for non-Hodgkin lymphoma.
A total of 44,330 men and women have died of pancreatic cancer thus far in 2018. The age-adjusted mortality rate has remained stable between 10.5 to 11.0 deaths per 100,000 over the last 40 years.
Trends in childhood cancer
Cancer is the second leading cause of death among children aged 1 to 14 years; nearly one in 279 children will be diagnosed with cancer before age 20, and approximately 175,000 young adults aged 20 to 39 years are childhood cancer survivors.
An estimated 15,700 children and young adolescents aged up to 19 years will be diagnosed with cancer in 2018, of which 1,700 will die from the disease.
Although cancer incidence has steadily increased over time for this population, mortality rates have continued to decrease, from 6.5 per 100,000 in 1970 to 2.3 per 100,000 in 2015, for an overall reduction of 67% among children and 61% among adolescents.
Improvements in treatment and inclusion in clinical trials have attributed to improved mortality rates. However, survivors are likely to experience comorbidities of the disease or treatment in adulthood.
“It is estimated that most pediatric cancer survivors have at least five comorbid conditions and that long-term survivors of childhood or adolescent cancers are eight times more likely to have a serious chronic health condition than siblings who had not been diagnosed with cancer,” Siegel and colleagues wrote.
Adverse events from therapy include growth retardation, cognitive impairment, cardiopulmonary difficulties, impairment of sexual function, infertility, posttraumatic stress disorder and secondary cancers.
“Current pediatric research is aimed at improving the treatments, making them more efficacious, and decreasing the temporary and permanent side effects of therapy,” the researchers wrote. “Although the significant success in pediatric cancer has spurred the discipline of ‘cancer survivorship,’ there is still much work to do.”
Disparities in cancer outcomes
Mortality rates vary for different populations based on race/ethnicity, economic and educational level or demographics.
“Many disparities are due largely to a failure to get adequate medical care to Americans who need it,” researchers wrote.
These include preventative care measures, vaccinations and cancer screening. New, effective health interventions commonly lead to widening disparities between populations that have access and those who do not.
Previous studies have demonstrated racial disparities in breast cancer early detection and treatment, including differences in quality of screening, surgery, dosing of chemotherapy and
completion of prescribed radiation therapy between blacks and whites.
“Although a high proportion of whites with breast cancer do not receive good care, a black or Hispanic woman is even less likely to receive optimal care,” researchers wrote.
Pathology difference also influence disparate outcomes. Nearly 22% of black patients with breast cancer have triple-negative disease compared with 12% of white patients, which has been determined as hereditary in nature, but also may be influenced by environmental factors.
“However, few appreciate that the largest portion of the black-white breast cancer mortality disparity is because of treatment inequalities for ER-positive disease, the subtype with the most available treatment options,” researchers wrote.
Among patients with colon cancer, studies have shown whites are more likely than blacks to be current for colorectal cancer screening, and that the quality of screening colonoscopy varies by race.
One study indicated that blacks appeared 30% more likely than whites to be diagnosed with an interval cancer, and more blacks received colonoscopies from physicians who had lower polyp detection rates (46.2% vs. 52.8%).
“This suggests that blacks are more likely to have a colonoscopy performed by less-skilled physicians, most likely because of differences in socioeconomic status rather than race,” researchers wrote.
Colorectal cancer pathology specimens also may be processed differently by race. For instance, black patients appear less likely to have an adequate number of lymph nodes removed by the surgeon for pathologic evaluation, and are more likely to be cared for in “busier hospitals where pathologists have heavier workloads and less time to process each surgical specimen,” the researchers wrote.
Black-white disparities also exist for prostate cancer, in part to higher incidence of disease among blacks.
Although black men treated in an equal-access system have prostate cancer survival rates comparable to those of white men, evidence suggests treatment is not equal.
“Blacks are also more likely to have elements of optimal care missing from disease management, including delays in treatment,” researchers wrote.
Geography can impact disparities, irrespective of race.
For example, although age-adjusted breast cancer mortality rates decreased by 39% between 1988-1990 and 2013-2015, 10 states reported only 20% to 29% decreases in mortality.
A 49% decrease in mortality related to colorectal cancer occurred between 1980-1982 and 2013-2015 in the U.S. However, eight states experienced a decrease between 12% and 31%.
Factors associated with geographic disparities include risk factors and access to screening and high-quality treatment, which may be heavily influenced by socioeconomic factors, legislative policies and distance to medical services.
Researchers identified education as one way to improve cancer control.
A lack of education, irrespective of race or location, is associated with greater risk for cancer mortality among all cancers except brain-related tumors.
“The cancers with the largest relative risks are those for which the disparity is most preventable,” researchers wrote. “These disparities largely reflect inequalities in the prevalence of cancer risk factors, such as smoking, obesity, physical inactivity, an unhealthy diet, and access to high-quality screening and treatment.”
Epidemiologists at American Cancer Society estimated that approximately 22% of all cancer deaths would not occur if all Americans had the cancer death rates of college-educated Americans, the researchers noted.
Further research indicated the Affordable Care Act allowed greater access to preventive, diagnostic and treatment services for cancer.
“This policy has resulted in a statistically significant 7% increase in insurance coverage, as well as a larger proportion of early-stage cancer diagnoses, among adults aged 19 to 25 years,” the researchers wrote. “It has also improved the prevalence of vaccination against HPV and increased receipt of fertility-sparing treatment for cervical cancer among young women.”
Despite a 25-year decline in the cancer mortality rate, cancer has remained the second leading cause of death in the U.S. and will likely eclipse cardiovascular disease to become the leading cause of mortality in the next decade, according to an editorial by Otis Brawley, MD, MACP, FASCO, FACE, chief medical and scientific officer at the American Cancer Society, and HemOnc Today Editorial Board Member, and colleagues wrote in an editorial that introduces the series of articles on cancer control..
“Review of the progress to date indicates that, although much good has been done, much more good can be done,” Brawley and colleagues wrote.
The additional articles in the series will summarize the current state of cancer in the U.S. and the need for better implementation of currently available interventions to further assist in reducing cancer incidence and mortality rates.
“When there are sufficient data to make a projection, estimates of the potential effect of cancer control interventions are included,” Brawley and colleagues wrote. “Of course, we must continue to support scientific research and innovation, as the future promises even greater benefit.
“It is our hope that this blueprint will be a call to action for cancer patients, family members of cancer patients, professional organizations, government agencies, the medical profession, academia, and industry to work together to implement what is known about cancer control,” they added. – by Melinda Stevens
: Siegel, Brawley and other authors report employment with the American Cancer Society, which received a grant from Merck for research outside the study.