Cancer diagnoses have become more common among young Americans, and a new study published in the Annals of Internal Medicine has found the trend is also a problem worldwide. In over 75 percent of countries studied, young adults had increasing diagnoses for several types of cancer.
Why are more young people getting diagnosed with cancer? One argument is that for some cancers, like colorectal cancer, higher rates could be attributed to an increase in routine screenings. However, the new study suggests another possibility.
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The researchers collected cancer data from 2003 to 2017 across 42 countries in 6 continents. They focused on 13 cancer types that had been linked to increasing cancer rates in young adults between 20 to 49 years old and older adults defined as over 50. These included:
- Leukemia
- Colorectal cancer
- Stomach cancer
- Breast cancer
- Prostate cancer
- Endometrial cancer
- Gallbladder cancer
- Kidney cancer
- Liver cancer
- Esophageal cancer
- Oral cancer
- Pancreatic cancer
- Thyroid cancer
In over 75 percent of countries studied, diagnoses for six cancer types, thyroid, breast, colorectal, kidney, endometrial, and leukemia, rose amongst young adults. Older adults also experienced similar increases in diagnoses for the same cancers with the exception of colorectal cancer. Young adults showed higher rates of colorectal cancer than older adults for 69 percent of countries studied.
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It wasn’t all bad news, though. Liver, oral, esophageal, and stomach cancer diagnosis rates went down in young adults in over 50% of countries.
The six types of cancer had one thing in common—all are obesity-related. According to the World Health Organisation, adult obesity has more than doubled since 1990 worldwide. It’s estimated that 1 in 8 people are obese. Of all the diagnoses among young adults, the study found endometrial and kidney cancer the most strongly associated with obesity.
“It increases chronic inflammation, which increases the risk of cancer.” Steven Lo, MD, the director of medical oncology and hematology at Stamford Health, explains. “Other hormonal imbalances, such as changes in Insulin, IGF-1, and adipokines, can stimulate cancer growth. Obesity also decreases the immune system, leading to increased cancer development.”
Alpa Patel, PhD, FACSM, the senior vice president of population science for the American Cancer Society, explains that obesity-related cancers used to be more of a concern in older generations because of mid-life weight gain. But in recent years, the concern has shifted more towards younger generations as excess fat accumulation is happening earlier and persisting through adulthood.
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The rate of childhood and adolescent obesity has tripled from 1990 to 2021 with 2050 projections estimating there will be more boys between 5 and 14 years old living with obesity than boys who are simply overweight.
Considering that the study only collected cancer data from high- and middle-income countries, it’s likely the rate of obesity-related cancer among young and older adults is much higher.
Rather than prioritising earlier screenings, Lo recommends people with obesity focus on maintaining a healthy weight through diet and exercise. “So much data show that individuals can reduce the risk of many cancers by following a healthy lifestyle. There is even very good data that shows that this can reduce cancer recurrence for individuals who already have early-stage cancers.”
This article originally appeared on Men’s Health US
