'Silver Tsunami' of Cancer Survivors to Slam US

Nick Mulcahy

July 25, 2016

There is a "silver tsunami" of aging, older cancer survivors in the United States "that is rapidly approaching," according to researchers at the National Cancer Institute (NCI).

The number of cancer survivors in the United States will increase by nearly 11 million over the next 24 years: from 15.5 million in 2016 to 26.1 million in 2040, report the study authors, led by Shirley M. Bluethmann, PhD, MPH, a postdoctoral cancer prevention fellow at the NCI.

But the proportion of survivors who are aged 65 years or older will represent nearly three quarters of cancer survivors by 2040 — a percentage that is considerably higher than the 61% reported for 2016.

The new report was published online July 25 in Cancer Epidemiology, Biomarkers & Prevention.

"U.S. demographics will literally change the face of the survivor population in the decades to come," the authors say.

The study authors were inspired to describe the coming boom of aging cancer survivors as a "tsunami" by "the data itself," Dr Bluethmann told Medscape Medical News.

"We noticed the 'wave-like' shape right away," she said, describing the dramatic rise and crest in cancer prevalence from 1975 (3.6 million) to 2040 (the aforementioned 26.1 million).

 
We noticed the 'wave-like' shape right away. Dr. Shirley M. Bluethmann
 

Multiple studies have described this huge swell of anticipated cancer in the United States, say the authors.

But the new report is unique in its focus on and breakout by older populations.

Specifically, the authors estimate that in 2040, survivors aged 65 to 74 years will account for 24% of all survivors; those 75 to 84 years old, 31%; and those 85 years or older, 18%.

Thus, 73% of survivors will be age 65 and older in 2040. Remarkably, in that year, just 18% of survivors will be age 50 to 64 years and only 8% will be younger than 50 years old.

These 2040 projected prevalence estimates in older age groups are huge percentage increases compared with the historical 1975 prevalence.

Namely, there is a 6-fold increase in cancer for those age 65 to 74 years, a 10-fold increase for those age 75 to 84 years, and a 17-fold increase for those age 85 years or older.

In performing the new study, the researchers used data from various sources, including population estimates from the US Census Bureau and cancer incidence and survival numbers from the Surveillance, Epidemiology, and End Results Program. Notably, prevalence projections were made assuming "constant future incidence and survival trends," the authors acknowledge. This may or may not be the case going forward, they admit.

"In reality, incidence has been declining slowly and steadily for most cancers, and survival, in turn, has increased," the authors write. But these concerns may all amount to a wash, they also say: "It is possible that these trends may balance each other (i.e., fewer cancer cases, but longer survival)."

Regardless of the exact numbers, there are plenty of uncertainties about how to best manage and treat older patients with cancer, suggest the authors.

"Cancer patients older than age 65 have been largely excluded from clinical trials, precluding opportunities to develop greater insight about the unique needs of older as well as long-term survivors," they write.

The authors cite chemotherapy as an example of a clinical issue that is not well studied in elders: "Greater participation by elderly survivors in clinical trials could provide more clarity in optimal dosing of chemotherapeutic agents, potentially reducing treatment-related toxicity for elderly cancer patients."

Cancer's Fellow Traveler: Comorbidities

With so many older projected cancer patients and survivors, the study authors also examined data to anticipate the "comorbidity burden" of these cancer survivors of the future.

The team examined and projected comorbidities across age-related subgroups using medical claims linked to cancer registry data.

"We noted some unexpected results," they said. For example, approximately 50% of survivors age 70 to 74 years experienced no comorbidities before diagnosis.

But the authors also acknowledged that their list of comorbidities was shorter than it might have been. Their analysis used a list of 16 comorbidities devised for longitudinal studies by Charlson et al (J Chronic Dis. 1987;40:373-883), but this list does not include common conditions that affect the elderly, such as hypertension, arthritis, atrial fibrillation, and chronic ischemic coronary artery disease. "As a result, comorbidity prevalence may underestimate the actual burden," they write.

Among cancer survivors, the three most prevalent comorbid conditions were congestive heart failure, chronic obstructive pulmonary disease, and diabetes.

Also, lung cancer survivors "consistently had the worst comorbidity burden of any cancer site across age groups," with nearly 50% of lung cancer survivors age 65 to 69 years experiencing severe comorbidity burden and 57% of survivors 85 years or older experiencing severe comorbidity burden.

Dr Bluethmann has disclosed no relevant financial relationships.

Cancer Epidemiol Biomarkers Prev. Published online July 25, 2016. Abstract

Follow Medscape senior journalist Nick Mulcahy on Twitter: @MulcahyNick.

Follow Medscape Oncology on Twitter: @MedscapeOnc

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