Research has shown that obesity accelerates the development of certain cancers, including cancers of the digestive tract, gynecologic cancers, and multiple myeloma. I led a team of researchers from the School of Medicine at Case Western Reserve University and Case Comprehensive Cancer Center to examine if a shift of obesity-associated cancer (OAC) burden toward younger age groups has occurred in recent years.
A Look at the Numbers
For a study published in JAMA Network Open, we analyzed 17 years of cancer data from the National Cancer Institute’s nationally representative Surveillance Epidemiology and End Results (SEER) database. The study examined the shift in age at the time of diagnosis between 2000 and 2016, and identified the specific race/ethnicity and sex-specific strata most affected by OAC from more than 6 million cases.
In the group aged 20-49, the change in the number of OACs ranged from a 5.9% decrease in Caucasian women to a 94.6% increase in Hispanic women during the study period. While the results showed an increase in both OACs and non-OACs among individuals aged 50-64, the increase was greater for OACs than for non-OACs and ranged from a 25.3% increase in Caucasian women to a 197.8% increase in Hispanic men. The highest increase in the number of cases was observed among Hispanic men, at 2.6% annually for OACs, compared with 1.5% per year for non-OACs (Table). Among individuals aged 65 or older, there was a decrease in the percentage of OAC cases across all race/ethnicity and sex-specific strata. In contrast, the percentage of non-OAC cases in this age group increased in Caucasian men and in women, regardless of their race/ethnicity.
The greatest increases in incident cases of OAC were observed in uterine cancer among Hispanic women (by over 200%), and in liver and thyroid cancers across all sex and race/ethnicity strata. Notably, the number of liver cases increased by more than 300% in the 50-64 age group among African-American women and Hispanic men.
Important Policy Implications
The importance of curbing the obesity epidemic cannot be overstated, not just to reduce cancer burden, but also to prevent premature morbidity and disability. Maintaining a healthy weight at all stages of life by promoting healthy dietary habits and physical activity is of highest priority. A shift of cancers to younger age groups implies that cancer is affecting people when they are at the height of their productivity, and the loss of potential years of life lost is substantial.
Given the financial toxicity associated with cancer, its treatment and recurrence, and end-of-life care, the impact on Medicare, Medicaid, and societal costs are significant. With more middle-aged individuals being diagnosed with cancer, people will increasingly transition to the Medicare program as cancer survivors potentially at younger ages and present with a greater burden of physical and mental comorbidities when compared with their cancer-free counterparts.
Our findings call for heightened vigilance by physicians to rule out cancer in younger individuals who present with symptoms suggestive of cancer. The old thinking of “too young for cancer” is not acceptable, given that younger people, as evidence suggests, are likely to present with more aggressive tumors and advanced-stage disease. For example, rectal bleeding in a young person should not be dismissed as a sign of hemorrhoids, but investigated to rule out colorectal cancer, especially in the presence of family history of colorectal cancer.
The results of our study highlight the importance of personalized cancer screening strategies, the parameters of which remain to be defined. While the specific criteria for personalized screening are being identified, symptoms and personal or family history of cancer should raise a red flag in the physician’s mind to rule out cancer, whether in the presence or absence of obesity.
Changes in Age Distribution of Obesity-Associated Cancers