In the US, many cancers are becoming increasingly common in young people – Technologist

Are younger generations more likely to contract cancer than their predecessors? This question frequently crops up in public conversation, but it’s also at the heart of recent intense research activity. A groundbreaking study, funded by the American Cancer Society and published in the August edition of The Lancet Public Health, offers insights into this issue in the specific context of the United States: According to its authors, led by epidemiologist Hyuna Sung (American Cancer Society), several forms of the disease are becoming increasingly common in young people.

For Americans born in the 1980s and 1990s, the risk of developing cancer is higher than in previous generations for 17 types of cancer (breast, pancreas, kidney, colon, small intestine, leukemia, thyroid, multiple myeloma, etc.). In contrast, for around 10 cancers – often associated with smoking – the risk is decreasing among younger people.

These results are specific to the situation on the other side of the Atlantic, and cannot be extrapolated to the rest of the world. However, the incidence of several cancers is rising among those under 50 in many countries, sometimes due to earlier diagnoses. As a sign of the concern of the scientific and medical communities, the number of publications on “early-onset cancers” has almost doubled in the last five years.

Sung and her co-authors analyzed the incidence and mortality (the number of new cases and deaths per year, per 100,000 people) of 34 cancers according to year of birth. They drew on data from national cancer registries and the US National Center for Health Statistics, gathering information from over 23 million patients affected by the disease between 2000 and 2019. Using the available data, they then estimated the lifetime frequency and mortality of each of these pathologies, according to year of birth from 1920 to 1990.

Improved diagnosis

“We found that IRRs increased with each successive birth cohort born [in the US] since approximately 1920 for eight of 34 cancers,” the researchers write. “Notably, the incidence rate was approximately two-to-three times higher in the 1990 birth cohort than in the 1955 birth cohort for (…) kidney and renal pelvis [+192%] and pancreatic [+161%] cancers in both male and female individuals; and for liver and intrahepatic bile duct cancer in female individuals [+105%].”

The incidence rates of nine other cancers (breast, colorectal, ovarian, etc.) initially decreased during the first half of the century before rising again among younger populations. In particular, the incidence of hormone-dependent breast cancer (the most common type) increased by 86% in the United States for the cohort born in 1990 compared to the one born in 1930. Between these same two cohorts, the incidence of uterine cancer rose by 169%, while that of cervical cancer fell by 60%.

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