A large new study from researchers at the American Cancer Society (ACS) has found that Generation X and Millennials in the United States are at a higher risk of developing 17 types of cancer compared to previous generations.
The study was published today in The Lancet Public Health.
Study Findings
The researchers found that cancer rates are continuing to climb in younger generations in 17 out of 34 types of cancer and that mortality rates have also increased in conjunction with several cancer types, including liver (in women only), uterine corpus, colorectal, gallbladder, and testicular cancers.
“These findings add to growing evidence of increased cancer risk in post-Baby Boomer generations, expanding on previous findings of early-onset colorectal cancer and a few obesity-associated cancers to encompass a broader range of cancer types.” Hyuna Sung, the study’s lead author and a senior principal scientist of surveillance and health equity science at the American Cancer Society, said in a press release.
Sung spoke with The Epoch Times about the study findings and discussed the potential environmental, lifestyle, and genetic factors that may help to explain the rise in cancer rates in younger generations.
“Recent evidence suggests excess body weight during early adulthood (ages 18–40 years) increases the risk of 18 different cancer types. Other suspected risk factors include unhealthy diet, sedentary lifestyle, altered sleep patterns, and environmental chemicals exposed during early life and young adulthood; however, studies that examined these associations among young people are limited. Genetic factors would not explain the rise in cancer incidence among younger generations,” she said in an email.
Researchers collected data from 23,654,000 cancer patients diagnosed with 34 types of cancer and 7,348,137 cancer deaths from 25 types of cancer from people between the ages of 25 and 84. The data was gathered over 20 years between Jan. 1, 2000, and Dec. 31, 2019, from the North American Association of Central Cancer Registries and the National Center for Health Statistics.
To understand how cancer rates have changed through different generations, the researchers grouped people according to their birth years, separated into five-year intervals—from 1920 to 1990. Researchers then adjusted the data for age and time-period differences to compare cancer rates and deaths among the different generations.
Researchers found that the number of new cases for eight out of 34 cancer types increased with each generation born since approximately 1920. For people born in 1990, the rates of pancreatic, kidney, and small intestinal cancers were two to three times higher compared to those born in 1955 in both men and women. Liver cancer rates showed a similar increase in women over the same period.
The number of new cancer cases increased in younger generations after initially declining in older generations in nine of the remaining cancer types, which include breast (estrogen-receptor positive only), uterine corpus (endometrial cancer), colorectal, non-cardia gastric (cancer of the main part of the stomach), gallbladder, ovarian, testicular, as well as anal and Kaposi sarcoma (cancer of the skin or mucus membranes) in men.
In the group born in 1990, cancer rates ranged from 12 percent higher for ovarian cancer to 169 percent higher for uterine corpus cancer compared to the group with the lowest rates.
Mortality rates also increased in these younger generations for certain cancers like liver cancer in women, uterine corpus, gallbladder, testicular, and colorectal cancers, in addition to the increasing incidence rates.
Sung said that six cancer types displayed particularly worrying trends in young people:
- Uterine corpus cancer (endometrial cancer)
- Colorectal cancer
- Breast cancer (estrogen-receptor positive)
- Gastric cancer
- Testicular cancer
- Liver cancer in young women
Promoting Health in Young People
In discussing preventive measures that might reduce cancer risk, Sung said she wants to emphasize systematic changes that encourage health promotion in younger generations.
“Despite many unknowns, emerging evidence suggests that early-lifetime exposures to well-established cancer risk factors, such as obesity, sedentary lifestyle, and unhealthy diet, increase the risk of early-onset cancers. Investing in education for health promotion and improving the built environment and school food systems for children and adolescents is crucial to reducing the risk of cancer and other chronic diseases.” Sung said.
She added that a good education empowers young people with the knowledge and skills needed to adopt healthier lifestyles, and a thoughtfully planned built environment can promote physical activity by offering safe places for exercise and play.
Moreover, a nutritious school lunch program provides children access to healthy meals, helping them establish healthy eating habits early on. It’s also crucial to teach them about the dangers of smoking and alcohol consumption, she said.
The Role of Obesity
When asked how significant a role obesity and other related metabolic conditions played in the increased incidences of these cancers, Sung told The Epoch Times that although the reasons are not entirely clear, at least for colorectal cancer, emerging evidence has made the connection between certain exposures that occur in adolescence or young adulthood, such as prolonged sitting, quality of the diet, consumption of sugar-sweetened beverages, consumption of alcohol, obesity, diabetes, metabolic syndrome, to developing young-onset colorectal cancer or its precursor.
“Obesity measured during young adulthood (18–40 years) has been linked to up to 18 types of cancers; however, for many other suspected risk factors, evidence is limited because of lack of information on early lifetime exposures in most epidemiologic studies.”
Future Research
As for where future research should be focused to understand the causes of the upward trends in cancer rates in younger generations, Sung said that more studies are needed to fully understand how exposure to certain risk factors early in life (beginning in prenatal stages, infancy, childhood, and adolescence) affects the chances of developing cancer later in life.
“Emphasis should be placed on potentially modifiable risk factors such as environmental factors and lifestyle factors to inform preventive strategies.”