Although results of other recent studies have noted the rise in the rate of obesity-related cancers among younger adults, this is the first study to also find a concurrent decrease in the rate of new cancer cases among patients 65 years and older.
An analysis of US cancer data published in JAMA Network Open shows that cancers related to obesity are on the rise in younger adults, and the investigators said the impact on Medicare and Medicaid in the coming decades will be severe unless screening programs can better pinpoint who is likely to develop the disease.
Siran Koroukian, PhD; Weichuan Dong, MA; and Nathan A. Berger, MD, examined records from more than 2.6 million obesity-related cancer cases and more than 3.4 million non—obesity-related cases in the Surveillance, Epidemiology, and End Results Program database from 2000 to 2016, looking not only at the age distribution but also at how obesity-related and non–obesity-related cancers were distributed by race and gender during that period.1
Although results of other recent studies have noted the rise in the rate of obesity-related cancers among younger adults, this is the first study to also find a concurrent decrease in the rate of new cancer cases among patients 65 years and older. “It is possible that changes in cancer surveillance over time have improved early cancer detection,” the investigators wrote.
In other words, the good news is that the screening protocols in Medicare are working. The bad news is that a different, more personalized screening approach is needed for younger adults, especially those aged 50 to 64 years. In this group, the rate of obesity-related cancers in particular is rising.
This latest study adds to concerns that the US obesity epidemic is thwarting gains in preventing and curing cancer. Overall, cancer survival rates have improved over the past quarter century, aided by declining smoking rates.2 In 2017, the CDC published data showing that 40% of all cancer diagnoses were of 13 types of cancer associated with obesity: adenocarcinoma of the esophagus; cancers of the gastric cardia, colon and rectum, liver, gallbladder, pancreas, breast (in postmenopausal women), ovaries, uterus, kidney, and thyroid; meningioma; and multiple myeloma.3
The JAMA Network Open study was the second this year to report a trend of obesity-related cancers among young patients. A February study in the Lancet Public Health by the American Cancer Society and the National Cancer Institute found that cancer incidence rose for 6 of 12 obesity-related cancers between 1995 and 2014 in adults aged 25 to 49 years, with steeper increases in younger generations.4
For the JAMA Network Open study, investigators defined obesity-related cancers as those of the colon and rectum, female breast, uterus, gallbladder and other biliary systems, esophagus, stomach, liver, pancreas, ovary, kidney and renal pelvis, and thyroid, as well as myeloma.1
The investigators noted the following findings:
• Of the obesity-related cancers in the study, 70.3% were among women, a result of the inclusion of breast, uterine, and ovarian cases.
• The study broke out incidence rates by age, gender, and race. In most cases, although the overall number of obesity-related cases among those 65 years and older rose because of the aging population, the incidence rate decreased. Among all race/gender groups in the population 65 years and older, obesity-related cancers decreased; other cancers increased or declined at lower rates.
• For the group aged 50 to 64 years, a statistically significant increase across the study period was observed in both obesity-related and non—obesity-related cancers; this was seen across all race/gender groups. The increases were larger in obesity-related cancers than in other cancers.
• Among those aged 20 to 49 years, the overall risk of cancer fell over the time, but all race/gender groups, with the exception of Hispanic men, saw a higher risk of obesityrelated cancers than other cancers.
What types of cancer are on the rise? Although the data showed a variation by age, race, and gender, liver and thyroid cancers rose sharply among many groups. Liver cancer is one of the fastest-rising cancer diagnoses in the United States, according to CDC.3
“The shift of the cancer burden to younger age groups has important public health, research, and policy implications,” the investigators wrote. When cancer is diagnosed in younger adults, the disease may already be more advanced and more aggressive.
Also, the authors noted that if more young adults develop obesity-related cancers in their 40s and 50s, more cancer survivors will join the ranks of Medicare, having endured the physical, financial, and emotional hardships of living with the disease. Because of the expense of current therapies and the cost-sharing designs of some health plans, many may also qualify for Medicaid.
“Together, these findings suggest an increasing cancer burden on Medicare and Medicaid programs in the future,” the investigators wrote. Reducing obesity may be the best solution, but short of that, the investigators recommended improving screening programs to catch cancer earlier or prevent it among younger adults. “The findings have important public health implications and suggest that interventions to reduce obesity and to implement individualized screening programs are needed,” the authors concluded. References
1. Koroukian SM, Dong W, Berger NA. Changes in age distribution of obesity-related cancers. JAMA Netw Open. 2019;2(8):e199261. doi: 10.1001/jamanetworkopen.2019.9261.
2. Cancer mortality milestone: 25 years of continuous decline. American Cancer Society website.pressroom.cancer.org/Statistics2019. Published January 8, 2019. Accessed August 15, 2019.
3. Steele CB, Thomas CC, Henley SJ, et al. Vital signs: trends in incidence of cancers associated with overweight and obesity—United States, 2005-2014. MMWR Morb Mortal Wkly Rep. 2017;66(39):1052-1058. doi: 10.15585/mmwr.mm6639e1.
4. Sung H, Siegel RL, Rosenberg PS, Jemal A. Emerging cancer trends among young adults in the USA: analysis of a population-based cancer registry. Lancet Public Health. 2019;4(3):e137-e147. doi: 10.1016/S2468-2667(18)30267-6.