HQ Team
August 4, 2024: Seventeen types of cancer are common in US millennials and the incidence rate for some forms is two to three times higher in people born in 1990 than in 1995, a study reveals.
Obesity, diet, and environmental toxins are the major contributing factors, according to the study published in the Lancet Public Health.
Other suspected risk factors such as unhealthy diet, sedentary lifestyle, altered sleep patterns, and environmental chemicals, during early life and young adulthood may have an effect and “remain poorly understood.”
Dietary patterns such as high saturated fats, refined grain, ultra-processed foods, and sugar, as well as meat versus plant diets, and sedentary behaviours during adolescence and young adulthood, have been associated with increased risk of some cancers, most consistently for colorectal and breast cancers.
Microbes
Specific microbes have also now been linked to oral and gastrointestinal tract cancers.
“The heightened cancer risk in recent birth cohorts has already translated into an increasing cancer morbidity and mortality burden in young adults, posing unique challenges to the healthcare system and community,” the authors wrote in an August 1 article.
Ten of 17 cancers with increasing incidence in younger birth groups are obesity-related cancers such as colorectum, kidney and renal pelvis.
Others include cancer of the gallbladder and other biliary, uterine corpus, pancreas, cardia gastric, and oestrogen receptor-positive breast.
Liver cancer
Ovarian cancer, myeloma, and liver and intrahepatic bile duct, included among the 10, suggested a potential role of obesity in emerging cancer trends in recent generations.
The findings expanded on the researchers’ previous study, in which eight cancer types increased in younger generations compared with older generations.
The new study, funded by the American Cancer Society, has looked at both cancer incidence, the number of new cases, and cancer mortality by birth year.
The researchers extracted data for 23,654,000 patients diagnosed with 34 types of cancer and 7,348,137 deaths from 25 cancers for the period Jan 1, 2000, to Dec 31, 2019.
Data was gleaned for 34 types of cancer and mortality data for 25 types of cancer for individuals aged 25–84 years for the period January 1, 2000, to Dec 31, 2019, from the North American Association of Central Cancer Registries and the US National Center for Health Statistics.
Cancer risk
“We found that incidence rate ratios increased with each successive birth cohort born since approximately 1920 for eight of 34 cancers.
“Notably, the incidence rate was approximately two-to-three times higher in the 1990 birth cohort than in the 1955 birth cohort. Additionally, the ratios increased in younger cohorts, after a decline in older birth cohorts, for nine of the remaining cancers.”
The findings add to growing evidence of increased cancer risk in younger generations and highlight the need to identify and tackle underlying risk factors, they said.
