Bottom Line: Improved cancer detection and treatment efforts, combined with demographic trends, are creating larger numbers of older cancer survivors who are likely to have other health conditions that impact care and well-being.

Journal in Which the Study was Published: Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

Author: Shirley M. Bluethmann, PhD, MPH, a cancer prevention fellow at the National Cancer Institute in Bethesda, Maryland.

Background: Researchers have been anticipating a growing number of older Americans, sometimes referred to as a "silver tsunami." Meanwhile, advances in cancer detection and treatment mean that more people are surviving cancer. "Understanding the impact of a graying nation on cancer prevalence is critical in informing efforts to design and implement quality cancer care for this population," said the study's lead author," Bluethmann said.

How the Study Was Conducted and Results: Bluethmann and colleagues based their study on incidence and survival data from 1975-2012, obtained from the Surveillance, Epidemiology, and End Results (SEER) Program. They projected U.S. cancer prevalence from 2016 to 2040 by using U.S. Census Bureau data, and applying the Prevalence Incidence Approach Model. SEER data linked with Medicare claims were used to estimate comorbidities commonly experienced in older adults, including health conditions such as heart disease, lung disease, or diabetes. The study showed:

• In 2016, there are approximately 15.5 million cancer survivors in the United States, and 62 percent of that group is 65 or older. By 2040, the study projects, there will be 26.1 million cancer survivors, and 73 percent of them will be 65 or older.
• The oldest age groups will come to represent a larger proportion of the population of cancer survivors. In 2040, survivors ages 65-74 will account for 24 percent of all survivors, those 75-84 will account for 31 percent of all survivors, and those 85 and older will represent 18 percent of all survivors. Compared with the prevalence estimates for 1975, the projected prevalence estimates in 2040 show a 6-fold increase for those 65-74 years, a 10-fold increase for those 75-84 years, and a 17-fold increase for those 85 years and older.
• Overall current cancer prevalence is similar between men and women of all ages. However, in older age groups, the disease is more prevalent among men. In the 65-69 age group, 14 percent of men and 12 percent of women have been diagnosed with cancer. The gap widens consistently as people age, and in the oldest group, age 90 and up, 37 percent of men and 25 percent of women have been diagnosed with cancer. Bluethmann said this gap is most likely related to higher numbers of prostate cancer survivors, which is typically diagnosed in men at older ages.
• Increasing age increases the chance that cancer survivors will suffer from one or more comorbid conditions. Among cancer survivors ages 65-69, 27 percent had a history of severe comorbidity. Among cancer survivors ages 85 and older, 47 percent had severe comorbid conditions.

Author Comment: Bluethmann said older adults are understudied, presenting challenges in delivering effective and age-appropriate cancer care. For example, she said, the comorbid conditions that many older adults experience may make them ineligible to participate in clinical trials.

"Because of this, we lack key data which would inform how geriatric populations would react to or benefit from precise cancer treatments or interventions," she said. Bluethmann said her study adds to evidence that shows that older adults often have complex health needs that must be addressed in efforts to deliver high-quality health care.

"We have known about the potential impact of the maturing baby boom generation for some time, but this study provides compelling, specific evidence of the impact of cancer on older Americans, now and in the future," Bluethmann said. "The changing demographics of this country are unmistakable, and it's time to rethink our approach to aging and cancer."

Limitations: Bluethmann noted that that the population projections are estimates, based on current cancer control efforts. Further, the researchers considered steady rates of incidence and survival to generate prevalence estimates. A shift in either of these trends over the long term could mean that that these results under- or over-estimate the true impact. However, these projections are believed to be the first to project cancer prevalence in an aging context to 2040.