Millennials and Gen X individuals have a higher risk of 17 different types of cancer, including breast and gastric cancers, according to a new study.
The large study published in The Lancet Public Health also found that the incidence rates increased with each successive generation born since about 1920 for eight out of 34 cancers.
For instance, researchers found that the incidence rate was two-to-three times higher in the millennial 1990 birth cohort than in the 1955 baby boomer birth cohort for pancreatic, kidney, and small intestinal cancers in both men and women.
Each birth cohort – or group of people classified by their birth year such as millennials born in the 90s and Gen X born in the mid-60s to mid-70s – share unique social, economic, political, and climate environments.
Researchers suspect this affects their exposure to cancer risk factors during their crucial developmental years.
In the study, scientists assessed health data from 23,654,000 patients diagnosed with 34 types of cancer for the period 1 January 2000 to 31 December 2019 from the North American Association of Central Cancer Registries.
They also analysed data on 7,348,137 deaths for 25 types of cancer for individuals aged 25–84 years for the same period from the US National Center for Health Statistics.
Researchers then estimated the generation-specific cancer incidence rate and death rate adjusted for age and period effects.
They found that across cancer types, the incidence rate among millennials ranged from 12 per cent for ovarian cancer to 169 per cent for uterine cancer, higher than the rate in the generation with the lowest incidence rate.
“The increase in cancer rates among this younger group of people indicates generational shifts in cancer risk and often serve as an early indicator of future cancer burden in the country,” Ahmedin Jemal, a senior author of the study, said.
Without effective interventions, scientists warn that a higher cancer risk in younger generations may lead to greater burden on the healthcare system in the future, “reversing decades of progress against the disease.”
They say the findings call for ensuring people of all ages have access to affordable, comprehensive health insurance – a key factor in cancer outcomes.
While the study could find cancer trends linked to each generation’s birth year, there is still no clear explanation for why these rates are rising.