A recent study has revealed an increase in cancer diagnosis rates among younger adults, primarily driven by significant rises in both women and individuals in their 30s.

A recent study reveals that specific types of cancer are being diagnosed more frequently in younger adults in the United States. The rise in cancer rates appears to be predominantly driven by cases among women and individuals in their 30s.

Conducted by 17 National Cancer Institute registries and funded by the government, the study, published in the journal JAMA Network Open on Wednesday, analyzed over 500,000 instances of early-onset cancer—cancers detected in patients under 50—between 2010 and 2019. The research found an overall increase in early-onset cancers over the decade, averaging 0.28% annually.

The changes seemed to be attributed to higher cancer rates among younger women, which increased by an average of 0.67% each year, while rates decreased among men by 0.37% annually.

For women, there were 34,233 early-onset cancer cases in 2010, rising to 35,721 in 2019—an increase of 4.35%, according to the study. Among men, cases decreased by 4.91%, from 21,818 in 2010 to 20,747 in 2019.

The study found an escalation in cancer diagnosis rates for adults in their 30s over the decade, whereas rates remained stable for other under-50 age groups. Simultaneously, cancer rates among adults aged 50 and older decreased.

When examining cancer trends among younger adults by race, the study found that early-onset cancers increased most significantly among individuals identifying as American Indian or Alaska Natives, Asians, and Hispanics. On average, early-onset cancer growth rates remained stable among White individuals and decreased among Black individuals from 2010 to 2019.

The most prevalent early-onset cancer cases diagnosed in 2019 were breast cancer (12,649 cases), thyroid cancer (5,869), and colorectal cancer (4,097).

The largest increases in early-onset cases were seen in appendix cancers, rising by 252%; bile duct cancers, increasing by 142%; and uterine cancer, with a 76% rise.

Incidence rates of early-onset cancers of the gastrointestinal tract experienced the most rapid growth from 2010 to 2019, with an almost 15% increase. Previous research has indicated a surge in digestive system cancers, particularly colorectal cancers, among adults under 55 since the 1990s.

These increases are not limited to the US, according to studies. An analysis of cancer registry records in 44 countries, published last year, revealed a rapid rise in early-onset cancer incidence for 14 types of cancer, many of which affect the digestive system.

The authors of that review suggested that the increase is partly due to more sensitive screening tests, as well as other factors that require further investigation.

Dr. Otis Brawley, Bloomberg Distinguished Professor of Oncology and Epidemiology at Johns Hopkins University, has proposed some theories regarding the rising rates.

“The largest cause of cancer in the United States right now is smoking, but smoking rates have been decreasing since the 1960s,” he stated. “In the next couple of years, the biggest cause of cancer in the United States is not going to be obesity, but it’s going to be obesity, excessive caloric consumption, and insufficient exercise. … I suspect that a significant part of this trend is lifestyle-driven, influenced by increased caloric intake, elevated obesity, and inadequate physical activity.”

Another potential factor is alcohol consumption, he added. “There has been a rise in alcohol-related cancers over the past few years. We estimate that about 6% of cancers in the United States are linked to alcohol consumption, especially binge drinking.”

To mitigate overall cancer risk, Brawley recommends “fundamental principles”: “Strive for a healthy weight, engage in exercise, maintain a balanced diet including five to nine servings of fresh fruits and vegetables per day, and reduce the consumption of processed foods.”