Generation X and millennials face a higher risk of getting certain types of cancer when compared to earlier generations, according to a large new study published Wednesday.
In the study, published in the Lancet Public Health journal, researchers from the American Cancer Society (ACS) studied 34 of the most common cancers. They found that cancer incidence rates continued to rise in progressively younger generations in 17 of the cancers, including breast, pancreatic and gastric cancers.
For eight of the 17 cancers, researchers found that cancer incidence rates rose for each successive birth cohort since 1920. For nine of them, incidence rates increased in younger cohorts, after first declining in older birth cohorts.
“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, lead author of the study, said in a statement.
The study highlighted the need to identify and address the “underlying risk factors in Gen X and Millennial populations” to explain and address these rising cancer rates in younger generations, said Ahmedin Jemal, a senior author of the study.
“Birth cohorts, groups of people classified by their birth year, share unique social, economic, political, and climate environments, which affect their exposure to cancer risk factors during their crucial developmental years,” Sung added.
“Although we have identified cancer trends associated with birth years, we don’t yet have a clear explanation for why these rates are rising,” Sung added.
The study was conducted using data from more than 23 million patients diagnosed with 34 types of cancer during the period beginning Jan. 1, 2000, and ending Dec. 31, 2019. The study also looked at mortality data from more than 7 million deaths for 25 types of cancers during the same period of time. The individuals were all between the ages of 25 and 84.
The researchers then calculated the incidence rate ratios of each birth cohort, adjusted for “age effect and period effect.”
The cancer incidence rate for the youngest birth cohort, 1990, ranged from 12 percent higher than the birth cohort with the lowest rate, for ovarian cancer, to 169 percent higher than the birth cohort with the lowest rate, for uterine corpus cancer.
The cancer incidence rate was also two-to-three times higher for the 1990 birth cohort than for the 1955 birth cohort for pancreatic, kidney, and small intestinal cancers.
Jemal warned of the implications of such rising cancer rates.
“The increase in cancer rates among this younger group of people indicate generational shifts in cancer risk and often serve as an early indicator of future cancer burden in the country. Without effective population-level interventions, and as the elevated risk in younger generations is carried over as individuals age, an overall increase in cancer burden could occur in the future, halting or reversing decades of progress against the disease.”
