A new study from the American Cancer Society has found that Generation X and millennials are more likely to develop many types of cancer compared to older generations. This study adds to growing evidence showing that cancers like those of the bowel, breast, and pancreas are becoming more common in younger people.
How the Study Was Conducted?
The research team looked at data from nearly 24 million cancer patients collected from U.S. cancer registries over a 20-year period, starting in 2000. They sorted the data by cancer type, sex, and the five-year period in which the patients were born, known as birth cohorts. To make sure the results were accurate, they adjusted the data to account for the fact that, generally, the older you are, the more likely you are to develop cancer.
By analyzing the rates of the 34 most common cancers—those with at least 200,000 cases over the two decades—the study provides the clearest picture yet of how many people are getting cancer, and when and why they are getting it.
Disturbing Trends in Cancer Rates Among Younger People
The study’s findings are alarming. It revealed that 17 different cancers are becoming more common among younger generations. For instance, people born in 1990 are two to three times more likely to develop cancers of the small intestine, thyroid, kidney, and pancreas than those born in 1955. Additionally, it was found that younger generations are getting cancer at earlier ages. Among all cancers and age groups, the most dramatic increases were seen in pancreatic and small intestine cancers in people under 30.
For some cancers, like bowel cancer, the increased rates among younger generations have even reversed a previous trend of decline seen in older generations. This suggests that the progress made in public health is now being lost.
The Role of Lifestyle and Behavior
So, what’s causing this spike in cancer rates among Generation X and millennials? The answer likely lies in changes in lifestyle and behavior.
Poor diet and increasingly sedentary lifestyles are two likely culprits. Ten of the 17 cancers identified in the study, including bowel and breast cancer, have been linked to obesity. The United States, like many other countries, is experiencing an obesity epidemic, with rates climbing every year. There is growing evidence that obesity in childhood or early adulthood can increase the risk of some cancers. A related factor is the rise in consumption of ultra-processed foods, which have also been linked to an increased risk of cancer.
“Increased binge drinking, particularly in millennial women, was highlighted by the study’s authors as a cause of the increased rates of liver and esophageal cancers seen among this specific cohort.”
For men, the study noted a U-shaped trend for Kaposi’s sarcoma and anal cancer, meaning rates declined after an initial peak and then began rising again. These two cancers are associated with HIV infection, and after a period of declining rates, this trend was reversed for cohorts born from the mid-1970s onwards. This mirrors the recent resurgence in HIV infection rates in the U.S.
Infection with the human papillomavirus (HPV)—a sexually transmitted virus known to cause cervical cancer—may also be a factor in the rise in anal cancer rates. It’s estimated that 90% of anal cancers are caused by HPV infection.
Interestingly, while anal cancer rates in men have gone up, the study observed a sharp decrease in cervical cancer risk for women born in the 1990 birth cohort—the first to have been vaccinated against HPV. When HPV vaccines were first introduced, they were only given to girls, meaning that young men in this generation were not protected.
Unexplained Increases in Some Cancers
While some of the changes in cancer rates can be explained by shifts in lifestyle and behavior with known links to cancer, these factors don’t account for all the increases observed, such as those in leukemia. The study’s authors note that more research is needed to understand the causes of these cancers. Without fully understanding why these cancers are becoming more common, it will be difficult to take the right steps to reverse these trends.
It Declines in Certain Cancers
It’s not all bad news, though. Some cancers are becoming less common in younger generations. The study showed a steady decline in the risk of developing lung cancer for each successive generation. People born in 1990 are five times less likely to develop the disease compared to those born in 1955. Similar progress is being seen for melanoma, where people born in 1990 are at less risk than every other cohort born in the preceding 50 years.
These positive trends are the result of successful public health campaigns aimed at reducing tobacco use and promoting sun-safe behavior. They show how changing behavior and making healthier choices can lower the risk of getting cancer.
This study highlights a worrying trend of increasing cancer rates among younger generations, likely driven by changes in lifestyle and behavior. However, it also shows that positive change is possible. By understanding the factors behind these trends, we can take steps to reduce cancer risk and improve the health of future generations.
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