Scientists in England say 11 cancers are becoming more common in adults under 50, adding new urgency to a question that has puzzled doctors for years. Their new study suggests rising levels of overweight and obesity may be the strongest clue so far, but researchers stress it does not explain the whole trend.
The research was led by teams at The Institute of Cancer Research in London and Imperial College London and published in BMJ Oncology. It looked at cancer patterns in England from 2001 to 2019 and compared them with known cancer risk factors such as smoking, alcohol, diet, exercise, and body weight.
Which cancers are rising
The study found significant increases in 11 cancers among adults ages 20 to 49: thyroid, multiple myeloma, liver, kidney, gallbladder, bowel, pancreatic, womb lining or endometrial, mouth, breast, and ovarian cancers. Of those, bowel and ovarian cancer stood out because they were rising in younger adults without the same rise being seen in older adults.
Researchers said bowel and breast cancer make up the biggest share of these cases in younger adults, with about 11,500 diagnoses a year combined. Even so, cancer in younger people is still uncommon compared with older age groups.
Why obesity stands out
The researchers found that smoking, alcohol use, physical inactivity, low fiber intake, and red or processed meat consumption were either stable or improving over time, meaning those factors do not match the same rising pattern seen in cancer diagnoses. The one major trend that did line up was the steady rise in overweight and obesity since the 1990s.
That does not mean obesity explains everything. The researchers estimated that in bowel cancer, about 20 out of every 100 extra cases in younger adults may be linked to excess weight, leaving most of the rise still unexplained. For endometrial cancer, the share linked to excess weight was estimated to be higher, around 35 in every 100 extra cases.
What scientists still do not know
The authors say the findings point to obesity as an important driver, but not the only one. They say other possibilities still need more study, including early life exposures, ultra processed foods, environmental chemicals, antibiotic use, inflammation, and changes in cancer detection.
That uncertainty matters because the rise in early onset cancer is not unique to England. Researchers and doctors in several countries have been trying to understand why more people in their 20s, 30s, and 40s are being diagnosed.
What experts are saying
Professor Montserrat García Closas of The Institute of Cancer Research said the news is worrying, but she also stressed that people can still lower their risk through a healthy lifestyle. The ICR said maintaining a healthy weight and staying physically active remain important ways to reduce cancer risk overall.
Researchers also emphasized that early onset cancer remains rare. According to the study team, about 1 in 1,000 people in their 20s, 30s, and 40s are diagnosed with cancer each year, compared with roughly 1 in 100 among people in their 50s, 60s, and 70s.
Why this study matters
This study does not solve the mystery of why cancer is rising in younger adults, but it gives scientists a stronger place to start. It suggests the answer is likely a mix of modern lifestyle, body weight, and other still unknown exposures that may begin much earlier in life than many people realize. That is an inference based on the study’s findings and the researchers’ own caution that obesity is only a partial explanation.
For families and doctors, the message is simple. Cancer in younger people is still uncommon, but unusual symptoms should not be ignored just because someone seems too young. Readers can review the BMJ Oncology study and the Institute of Cancer Research summary for the full findings.