A new study has identified 11 types of cancer that are on the rise among adults aged 20 to 49, with obesity emerging as a significant contributor to this worrying trend. Researchers from the Institute of Cancer Research, London (ICR) and Imperial College London analysed national cancer registry data for England from 2001 to 2019 and found increasing rates for thyroid, multiple myeloma, liver, kidney, gallbladder, colorectal, pancreatic, endometrial, oral, breast, and ovarian cancers.
Obesity's Role and Other Factors
All but oral cancer are known to be linked to excess weight. While the researchers caution that obesity does not fully explain the rise, they believe it plays a crucial role, potentially through elevated insulin levels and inflammation. In England, about 31,000 cancers were diagnosed in the 20–49 age group in 2023, roughly one in every 1,000 individuals, compared to 244,000 in the 50–79 group (one in 100). For nine of the 11 cancers, rates are increasing in both younger and older adults, but bowel and ovarian cancers are rising only in younger age groups.
Bowel Cancer and BMI
Bowel cancer rates in younger women linked to BMI rose faster (from 0.9 to 1.6 per 100,000) than those not linked to BMI (from 6.4 to 9.6 per 100,000). Similar patterns were seen in men. However, the overall number of BMI-linked cases remains lower, suggesting other factors are at play. Suspected contributors include ultra-processed foods, antibiotic use, and air pollution, but many of these have shown stable or declining trends in the UK, underscoring the need for further research.
Expert Commentary
Professor Montse García-Closas from the ICR stated: “Our main conclusion is that although BMI is our best clue, much of the increase still remains unexplained. It’s likely a combination of multiple factors that act together.” She added that around 15% of bowel cancer in younger people could be due to overweight or obesity, with 40–50% attributable to combined known risk factors like obesity, lack of exercise, alcohol, and smoking.
Among younger adults, breast cancer was most common (8,500 cases), followed by bowel (3,000) and melanoma (2,800). The study, published in BMJ Oncology, found that traditional risk factors like smoking and alcohol consumption remained stable or declined, while overweight and obesity have increased steadily since 1995. However, BMI alone does not explain the overall rise.
Call for Action
Professor Amy Berrington from the ICR noted: “Although rates have been increasing, cancer in young people is still a rare disease.” Professor Marc Gunter from Imperial highlighted that obesity is a known risk factor for 19 cancers, partly due to higher insulin levels and inflammation. The researchers called for large, long-term studies to identify all contributing factors but stressed that the evidence on obesity is strong enough to make it a public health priority, especially in children and young people.
Michelle Mitchell, Cancer Research UK’s chief executive, said: “Preventing cancer cases must be a priority for the UK Government. Measures to restrict advertising of junk food and make nutritious food more accessible would help people keep a healthy weight.”
