Gen X Projected to Experience Greater Increases in Cancer Incidence than Previous Generations
, by Elise Tookmanian, Ph.D.
A goal of the Cancer Moonshot 2.0 is to reduce age-adjusted cancer mortality in the U.S. by 50% by 2047; incidence patterns will influence that target. Trends for many cancers have declined, while the incidence of some is increasing in younger age groups. However, underlying patterns by birth year remain unclear. In this study, researchers used cutting-edge statistical tools to determine if cancer incidence in successive social generations is increasing or decreasing. Unexpectedly, they project that members of Generation X (born between 1965 and 1980) will experience larger per-capita increases in the incidence of leading cancers combined than any prior generation. This study was published on June 10, 2024, in JAMA Network Open.
The study, led by Philip S. Rosenberg, Ph.D., senior investigator in the Biostatistics Branch, used data on 3.8 million individuals with invasive cancer from the NCI Surveillance, Epidemiology, and End Results (SEER) Program from 1992-2018. They used the latest version of a tool called the age-period-cohort model to capture the net impact of these three factors. Age effects may reflect the underlying biology of cancer, such as the role of aging, while period effects are temporal trends relating to a specific event, such as the introduction of a new carcinogenic exposure or changes in diagnostic criteria. Finally, birth cohort effects are generational, potentially related to collective lifestyle changes or environmental exposures experienced at the same life stage (e.g. puberty).
When comparing projected cancer incidence for Generation X and Baby Boomers (born 1946 – 1964) at age 60, the researchers found that numerically, cancers with increasing incidence have overtaken cancers with decreasing incidence in Generation X. Specifically, in females, declines in lung and cervical cancers have been overtaken by increases in thyroid, kidney, rectal, uterine, colon, pancreatic, and ovarian cancers as well as non-Hodgkin lymphoma and leukemia. Among males, declines in lung, liver, and gallbladder cancers and non-Hodgkin lymphoma have been overtaken by increases in thyroid, kidney, rectal, colon, and prostate cancers and leukemia. Many of the cancers that are projected to increase are also associated with obesity and sedentary lifestyle, two risk factors that have been increasing over the lifespan of Gen X. If current trajectories continue, cancer incidence in the U.S. could remain high for decades.
The main limitation of this study is that the conclusions are projections derived from modeling. Additional analyses in other U.S. as well as global cancer registries are needed to tease out any geographic or other nuances in these data. Given the concerning net increases in new cancer cases among Generation X suggested by the models, the researchers call for research to identify contemporary causes of cancer and explore novel means for prevention. NCI is investigating both of these areas through a new prospective cohort, the Connect for Cancer Prevention Study (Connect). Connect is recruiting participants over a wide age range (30-70), including contemporary birth cohorts like Generation X and Millennials, capturing serial information on novel, suspected, and known risk factors, and collecting repeat biospecimens that will allow study of novel cancer causes and new approaches to cancer prevention.
Reference
Rosenberg PS and Miranda-Filho A. Cancer Incidence Trends in Successive Social Generations in the United States. JAMA Netw. Open. 2024.