More Data Show Shift to Obesity-Related Cancers in Younger Patients

Another analysis of US cancer data published this week shows that cancers related to obesity are showing up in younger adults, and the researchers say the impact on Medicare and Medicaid in 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 cancer cases in the Surveillance, Epidemiology, and End Results (SEER) database from 2000 to 2016, looking not only at the age distribution but also how obesity-related and non–obesity-related cancers were distributed by race and gender during that period.¹

Although other studies in recent years have noted the rise in the rate of obesity-related cancers among younger adults, this is the first that also found a concurrent decrease in the rate of new cancer cases among patients age 65 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 age 50 to 64. In this age group, obesity-related cancers in particular are rising.

The latest study adds to concerns that the US obesity epidemic is thwarting other gains in preventing and curing cancer. Overall, cancer survival rates have improved for the past quarter century, aided by declining smoking rates.² In 2017, CDC published data that showed 40% of all cancer diagnoses were associated with 13 types of cancer associated with obesity: adenocarcinoma of the esophagus, cancers of the gastric cardia, colon and rectum, liver, gallbladder, and pancreas; and cancers of the ovaries, the uterus, the kidney, and the thyroid.³ A February 2019 study in The Lancet 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, with steeper increases in younger generations.⁴

For this new study, researchers defined obesity-related cancers as those of the colon and rectum, female breast, uterus, gallbladder and other biliary, esophagus, stomach, liver, pancreas, ovary, kidney and renal pelvis, thyroid, and myeloma.¹

The investigators found the following:

• Of the obesity-related cancers in the study, 70.3% were among women, due to the inclusion of breast, uterine, and ovarian cases.
• The study broke out incidence rates by age, gender, and race; in most cases, while the overall number of obesity-related cases among those age 65 and older rose due to aging population, the incidence rate decreased. Among all race/gender groups in the population age 65 and older, obesity-related cancers decreased; other cancers increased or declined at lower rates.
• For the 50 to 64 year old age group, there was a statistically significant increase across the study period 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 for other cancers.
• Among those 20 to 49 years of age, the overall risk of cancer fell over the time, but all race/gender groups saw a higher risk of obesity-related cancers than other cancers except Hispanic men.

What types of cancer are were on the rise? While there was variation by age, race, and gender, liver and thyroid cancers rose sharply among many groups, the data show. Liver cancer is one of the fastest-rising cancer diagnoses in the United States, according to CDC.²

The study found:

• Cancer types that increased among white women aged 50 to 64 included thyroid, liver, melanoma, and kidney cancers; in black women, cases rose 2- to 3-fold for liver, thyroid, and uterine cancers; cases more than doubled for gallbladder, pancreas and stomach cancers.
• In black men aged 50 to 64, cases doubled for gallbladder, liver, thyroid, and kidney cancers. Among black men aged 20 to 49 years, the largest increases were for thyroid and kidney cancers and myeloma.
• Among Hispanic men, the largest increase in the 20- to 49-year-old age group was seen in thyroid (up 179%); this cancer rose 300% in the 50- to 64-year-old age group, while liver cancer rose 350%. Kidney cancer rose 200% in both groups.
• Hispanic women in the 50- to 64-year-old age group saw a 400% increase in thyroid cancers over the study period; kidney, uterine, pancreatic cancers and melanomas rose more than 200%.

“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, this will mean more cancer survivors will join the ranks of Medicare, having endured the physical, financial, and emotional hardships of living with the disease. Due to the expense of today’s 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,” they wrote.

Reducing obesity may be the best solution, but short of that, the investigators recommend improving screening programs through better risk stratification 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 Open. 2019;2(8):e199261. doi:10.1001/jamanetworkopen.2019.9261.
2. Cancer mortality milestone: 25 years of continuous decline. American Cancer Society website. http://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 Mort Wky Rpt. 2017;66(39):1052-1058.
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.