Cancer Mortality Rate Declines as Advances in Cancer Treatment and Management Arise

Cancer mortality has been on a continuous decline since its peak in 1991, resulting in an overall reduction of 31% in the mortality rate and approximately 3.2 million fewer cancer deaths in the United States, according to a report by the American Cancer Society on cancer statistics.

This progress is due in part largely to reductions in smoking and subsequent declines in lung cancer mortality, which has occurred as a result of improved management and treatment approaches for non–small cell lung cancer (NSCLC). These breakthroughs also contribute to the rapid reductions in mortality from hematopoietic and lymphoid malignancies and more recently in specific difficult-to-treat cancers like metastatic melanoma.

The findings from this report, however, demonstrated a slowing of early diagnosis through screening in cancers amenable to early detection, such as breast cancer, prostate cancer, and colorectal cancer (CRC). This report also highlighted concerns regarding persistent racial, socioeconomic, and geographic disparities for highly preventable cancers like cervix and lung.

The report compiled the most recent data on population-based cancer occurrence. Through 2017, incidence data were collected by the Surveillance, Epidemiology, and End Results Program; the National Program of Cancer Registries; and the North American Association of Central Cancer Registries. Through 2018, mortality data were collected by the National Center for Health Statistics. The report estimated the numbers of new cases and deaths in the United States. Additionally, mortality data were collected by the National Center for Health Statistics through 2018.

In 2021 in the United States, the report estimates approximately 1,898,160 cancer cases will be diagnosed, which is equal to 5200 new cases per day. The cancer death rate had been rising for most of the 20th century, but the rate has now been on a continuous decline from 1991 to 2018, which resulted in a total decline of 31%.

In the 4 leading cancer types, long-term declines in mortality were halted for prostate cancer, slowed for breast cancer and CRC, but accelerated for lung cancer, which accounted for around half of the total mortality decline from 2014 to 2018. In men, the annual decline in lung cancer mortality doubled from 3.1% from 2009 through 2013 to 5.5% during 2014 through 2018, and among women, the rate increased from 2.4% to 5%, respectively.

This trend in lung cancer mortality coincides with steady declines observed in incidence as well, declining by about 2.2% to 2.3% per year. The 2-year relative survival rate among patients with lung cancer also increased from 30% during 2009 through 2010 to 36% during 2015 to 2016, and among those with NSCLC specifically, the 2-year survival rate rose from 34% to 42%, respectively, with absolute gains of 5% to 6% for every stage of diagnosis. A large part of this is due to the advances in the field that have improved outcomes for these patients, such as the addition of EGFR tyrosine kinase inhibitors and immunotherapy to the treatment landscape.

The most common cancers diagnosed among men include prostate cancer, lung and bronchus cancer, and CRC, accounting for 46% of all incidences of cancer in men; prostate cancer alone accounts for 26% alone. Among women, the most common include breast cancer, lung cancer, and CRC, with breast accounting for 30% of female cancers alone. The probability of being diagnosed with an invasive cancer is slightly higher for men at 40.5% compared with women at 38.9%, which shows differences in life expectancy and cancer risk.

Over time, the sex disparity in overall cancer incidence has narrowed; the male-to-female incident rate ratio dropped from 1.39 (95% CI, 1.38-1.40) in 1995 to 1.14 (95% CI, 1.13-1.14) in 2017, which is due to incidence rates declining during this period of time by 2% among women versus 20% among men.

“Reasons for sex differences are not fully understood but probably largely reflect differences in exposure to environmental risk factors and endogenous hormones, as well as complex interactions between these influences. Sex differences in immune function and response may also play a role,” Siegel et al wrote.

Cancer remains the second leading cause of death in the United States after heart disease, both among men and women, but cancer is the leading cause of death in many states, as well as people who are Hispanic, Asian American, or Alaskan Native. The occurrence of cancer and outcomes vary between racial and ethnic groups considerably, which is largely due to inequalities in wealth causing differences in risk factor exposures, as well as barriers to high-quality prevention, early detection, and treatment.

Due to higher rates of lung and female breast cancers in this group, non-Hispanic Caucasians have higher rates of overall cancer incidence, but sex-specific incidence is higher in non-Hispanic African American men. The rates were 81% among non-Hispanic African American men than in Asian/Pacific Islander men who have the lowest rates, and the rates were 7% higher than non-Hispanic Caucasian men.

Among women, non-Hispanic Caucasians have the highest incidence, which is 9% higher than non-Hispanic African Americans. Non-Hispanic African Americans, however, had the highest sex-specific cancer mortality rates were 12% higher than non-Hispanic Caucasian women.

Differences in detection practices and the prevalence of risk factors, such as smoking, obesity, and other health behaviors, vary across states, with the largest geographic variation being the most preventable cancers, including lung cancer, cervical cancer, and melanoma of the skin. Study authors concluded that the persistent racial, socioeconomic, and geographic disparities for highly preventable cancers are concerning.

“Increased investment for both the equitable and broad application of existing cancer control interventions and basic and clinical research to further knowledge and advance treatment options would undoubtedly accelerate progress against cancer,” Siegel et al concluded.

_References

_{Siegel RL, Miller KD, Fuchs HE, et al. Cancer Statistics, 2021. CA Cancer J Clin. 2021. 71:7-33. doi: 10.3322/caac.21654}