according to a new analysis.
Researchers found that rates for all cancers combined declined by 27% overall between 1971 and 2019 and decreased significantly for 12 of the 15 top cancer sites analyzed.
The data revealed even greater mortality declines for certain cancers in particular years. For example, mortality from lung cancer was 44% lower in 2019, compared with its peak rate in 1993, whereas it was only 13% lower, compared with morality rates in 1971.
“The cancer mortality rate has reduced considerably since 1971 overall and for most cancer sites because of improvements in prevention, early detection, and treatment,” lead author Ahmedin Jemal, DVM, PhD, American Cancer Society, Kennesaw, Ga., and colleagues wrote.
Advances in surgery, radiotherapy, chemotherapy, precision medicine, and combinations therapies over the past 5 decades have contributed to these significant declines in mortality, Dr. Jemal and colleagues explained. The researchers also credit the “expanded investment” in the National Cancer Institute’s annual budget following the 1971 National Cancer Act, which increased the budget 25-fold from $227 million in 1971 to $6 billion in 2019.
The report, published online Nov. 11, 2021, in JAMA Oncology, analyzed mortality rates for all cancers as well as the top 15 sites using the National Center for Health Statistics.
The researchers found that, overall, deaths declined significantly for all cancers over the study period. Some of the biggest headway since 1971 occurred for stomach and cervical cancers – with 72% and 69% lower mortality rates, respectively – as well as colorectal cancer (56%), oral cavity and pharynx cancer (43%), and ovarian cancer (41%). Mortality rates of female breast cancer and prostate cancer also dropped considerably – both by 39%.
“The decline in mortality for female breast, cervical, colorectal, and prostate cancer in part reflects increased detection (and removal) of premalignant lesions and early-stage cancers,” Dr. Jemal and colleagues noted.
Data suggest that screening likely explains about half of the observed decline in mortality from colorectal cancer between 1975 and 2002. A 2018 study also found that the use of adjuvant chemotherapy was responsible for 63% of the decline in mortality from female breast cancer between 2000 and 2012.
In addition, the authors noted, “the decline in lung, oral cavity and bladder cancers largely reflects reductions in smoking because of enhanced public awareness of the health consequences, implementation of increased cigarette excise taxes, and comprehensive smoke-free laws.”
However, mortality did increase in a few categories. For instance, the mortality rate from pancreatic cancer increased by 3% between 1971 and 2019, and by 8% for both esophageal and brain cancers. Mortality rates from cancer were also greater for 29% of the U.S. counties included in the analysis, mostly those in the South.
The increase in mortality from pancreatic cancer likely reflects the growing rates of obesity in the United States, along with no real advances in pancreatic cancer prevention, early detection, or treatment, the authors suggested. In addition, lack of progress in regions of the south may be related to unequal access to improvements in treatment compared with other parts of the country.
“Improving equity through investment in the social determinants of health and implementation research is critical to furthering the national cancer-control agenda,” the authors concluded.
The authors disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.