A recent study highlights a concerning rise in 11 types of cancers among individuals aged 20 to 49, linking obesity as a noteworthy factor driving these increasing rates in people under 50.
The cancers identified include thyroid, multiple myeloma, liver, kidney, gallbladder, colorectal, pancreatic, endometrial, oral, breast, and ovarian cancers.
Research indicates that, aside from oral cancer, all the other types identified are associated with excess weight. While experts caution that obesity alone doesn’t account for this trend and that additional evidence is needed, they believe that being overweight may significantly contribute, possibly due to heightened levels of insulin and inflammation.
There’s been a growing unease over the rising incidences of cancers like bowel and ovarian in young adults. In England, around 31,000 cancer cases were diagnosed among 20 to 49-year-olds in 2023, translating to roughly one in every 1,000 individuals. In contrast, the 50 to 79 age group saw about 244,000 cases, which translates to approximately one in 100.
Nine out of the 11 cancers show rising rates in younger adults, but they are also increasingly found in older age groups, who are generally more susceptible to these diseases.
Notably, bowel and ovarian cancer rates are only escalating among younger populations. For instance, the rate of bowel cancer in younger women linked to BMI increased from 0.9 to 1.6 per 100,000 people, while non-BMI-related cases went up from 6.4 to 9.6 per 100,000. Similar trends were observed among men.
This research, conducted by the Institute of Cancer Research in London and Imperial College London, emphasizes that while BMI-related bowel cancer cases among younger women remain lower compared to those not linked to BMI, alternative factors must also impact this increase.
Several suspected influences—like ultra-processed foods, antibiotic use, and air pollution—have been raised in recent discussions. However, many of these have shown stable or declining trends in the UK, pointing to the necessity for a thorough exploration of all potential causes.
Professor Montse García-Closas from the Institute mentioned that further research is essential, but “we cannot wait to act.” She noted that data indicates that approximately 15% of bowel cancer cases in younger people may be attributed to being overweight or obese, with an overall contribution of 40% to 50% from combined known risk factors like lack of exercise, alcohol consumption, and smoking.
She stated: “Although BMI is our best clue, much of the increase still remains unexplained. Additional analysis suggests that it’s likely due to various factors working together.”
Among the younger group, breast cancer was the most prevalent, with 8,500 cases reported, followed by bowel cancer at 3,000 and melanoma skin cancer with 2,800 instances.
Interestingly, despite the rise in cancer rates among younger adults over the last two decades, most established risk factors—like smoking, alcohol use, consumption of red or processed meats, low fiber diets, and insufficient exercise—have either remained stable or declined prior to diagnosis. This raises questions about their role in the recent surge of cancer cases.
Research indicates that rising rates of overweight and obesity—steadily climbing since 1995—could play a crucial role in the increase of cancer diagnoses. However, the study published in BMJ Oncology indicates that BMI increases alone cannot wholly account for the broader trend of rising cancer rates among younger adults in England.
There are likely other causes, whether known or still undiscovered, that also contribute to this rise. Notably, most cancers rising in younger demographics are also on the upswing in older adults, implying shared causes.
From 2001 to 2019, researchers found that around 20% of bowel cancer increases could be explained by rising BMI during that time.
Professor Amy Berrington from the Institute stated: “While rates have indeed been climbing, cancer among young people is still relatively rare.”
Moreover, Professor Marc Gunter from Imperial noted that obesity is a recognized risk factor for about 19 different cancers, suggesting that certain cancers, like colorectal cancer, might be influenced by higher hormone levels such as insulin, which is often elevated in individuals suffering from obesity.
He mentioned: “Insulin has been linked to cancer, particularly in recent studies concerning early-onset colorectal cancer, and this remains an active area of investigation.”
The researchers are advocating for extensive, long-term studies to discern all biological and environmental factors impacting rising cancer rates in younger adults. They believe obesity should be addressed as a public health priority, especially with a focus on reducing obesity in children and young people.
In the study, national cancer registry data from England (2001-2019) was utilized. Addressing obesity across all age groups, particularly in younger populations, through stronger public health policies and better access to effective interventions could potentially slow down cancer rates and prevent numerous cases, which must become a national focus.
Michelle Mitchell, chief executive of Cancer Research UK, remarked on the small increase in cancer incidence among adults under 50, noting that while the situation is complex and requires further investigation, this study offers valuable insights. “Obesity doesn’t fully explain the trend, and improvements in detection may also contribute, meaning more individuals are diagnosed at earlier ages. Preventative measures should be a primary goal for the UK government,” she added, emphasizing smoking remains a leading cause of cancer in this demographic.
She concluded by advocating for measures to restrict junk food advertising, enhance tracking and targets for healthy food sales, and improve access to nutritious options for all as methods to help maintain a healthy weight.
