In a major development, the American Cancer Society (ACS) conducted a thorough analysis that revealed a concerning trend, that Generation X and millennials in the United States had much higher odds of developing 17 forms of cancer than previous generations. The Lancet Public Health published this study, revealing an increased trend in cancer incidence and mortality rates among younger cohorts, thereby raising concerns about the future burden of cancer.

Dr. Hyuna Sung, the study's lead author and a senior principal scientist of surveillance and health equity science at the American Cancer Society, stated, "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."

The study examined data from more than 23.6 million cancer diagnoses and 7.3 million cancer deaths among people aged 25 to 84, from January 1, 2000 to December 31, 2019. The data came from the North American Association of Central Cancer Registries and the National Center for Health Statistics in the United States. The researchers analyzed cancer rates across generations using birth cohort-specific incidence and mortality rate ratios, with a focus on people born between 1920 and 1990.

Key findings show that since 1920, the incidence rates of eight out of 34 cancer types have grown with each consecutive birth cohort. The two-to-three-fold increase in incidence rates for pancreas, kidney, and small intestinal cancers in both males and females, as well as liver cancer in females, between the 1990 and 1955 birth cohorts is especially concerning. Other cancers with higher incidence rates in younger cohorts include breast cancer (estrogen-receptor positive exclusively), uterine corpus cancer, colorectal cancer, non-cardia gastric cancer, gallbladder cancer, ovarian cancer, testicular cancer, anal cancer in men, and Kaposi sarcoma in males. The incidence rate in the 1990 birth cohort was much higher, ranging from 12% for ovarian cancer to 169% for uterine corpus cancer, when compared to the cohort with the lowest incidence rate.

Dr. Ahmedin Jemal, senior vice president of surveillance and health equity science at the ACS and the study's senior author, emphasized the implications: "The increase in cancer rates among this younger group of people indicates generational shifts in cancer risk and frequently serves as an early indicator of future cancer burden in the country." Without effective population-level therapies, and as the increased risk in younger generations is passed on as people age, an overall increase in cancer burden could occur in the future, stalling or reversing decades of success against the illness."

While the study provides a detailed review of cancer patterns by birth cohort, the causes for the growing rates are unknown. "Birth cohorts, or groups of people identified by their birth year, have distinct social, economic, political, and climate settings that influence their exposure to cancer risk factors throughout critical formative years. Although we have discovered cancer patterns based on birth years, we do not yet have a plausible explanation for why these rates are rising," Dr. Sung stated.

The rising cancer burden among younger generations emphasizes the importance of comprehensive public health interventions and legislative measures. Lisa Lacasse, president of the American Cancer Society Cancer Action Network (ACS CAN), emphasized the importance of healthcare access: "The rising cancer burden among younger generations highlights the importance of ensuring that people of all ages have access to affordable, comprehensive health insurance, which is a key factor in cancer outcomes. To that end, ACS CAN will continue our long-standing efforts to urge lawmakers to expand Medicaid in states that have yet to do so, as well as to advocate for the permanent extension of the enhanced Affordable Care Act tax subsidies that have provided millions with access to care."

The ACS report underscores a key public health issue: Generation X and millennials had higher cancer risks than prior generations. This trend calls for targeted research to uncover underlying risk factors and adopt effective preventative interventions. As Dr. Jemal correctly mentioned, identifying and treating these generational variations in cancer risk is critical to avoiding a rise in the overall cancer burden in the future.