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Groundbreaking new research is warning of a worldwide increase in the incidence of obesity-related cancers among younger and older adult populations. The study, published in Annals of Internal Medicine, upends previous notions that some malignancies chiefly affect younger adults, effecting a shift in understanding cancer in the 21st century. Researchers, including from Imperial College London, assessed two decades of cancer patient data to show that obesity-driven carcinogenesis affected people across global regions and age groups. The study scrutinised annual cancer incidence data from 2003 to 2017, gathered from 42 countries in Asia, Europe, Africa, North and South America and Australasia through the International Agency for Research on Cancer’s GLOBOCAN database. The researchers analysed data on 13 cancer types identified in earlier studies as rising in younger adults, such as leukemia, colorectal, stomach, breast, prostate, endometrial, gallbladder, kidney, liver, oesophageal, oral, pancreatic, and thyroid cancers. They then segmented the patient cohorts into younger adults (20-49 years) and older adults (50 and above). This approach enabled the researchers to provide focussed insights into age-related cancer patterns, yielding unexpected findings. Counter to previous beliefs that some cancers were isolated among younger people, the research showed that six types of cancer – leukemia, thyroid, breast, endometrial, colorectal, and kidney – were showing rising incidence in younger and older adults in nearly three-quarters of the surveyed countries. These cancers, largely linked to obesity, showed broad effects across adulthood rather than being confined to specific age brackets, the researchers warned. Previous studies had established the link between obesity and cancer. Increased accumulation of fat tissue can induce inflammation across the body, change hormone levels, disrupt cell metabolism, and foster a pro-carcinogenic environment, scientists say. Uterus and kidney cancers showed the strongest associations with obesity in the study, highlighting how adipose tissue not only served as an energy reservoir but also as a hub for hormone production. When one’s hormone secretion profile is dysregulated, it can contribute to increased cell proliferation and impaired elimination of dead cells, accelerating tumour risk, the researchers say. Notably, the study found declining rates for liver, oral, food pipe and stomach cancers in the younger demographic, most likely due to successful public health interventions targeting tobacco use, alcohol consumption, and viral hepatitis. Gut cancer rates, on the other hand, appeared to be surging in younger adults more sharply than in their older counterparts. This could be due to enhanced screening and early detection efforts in older adults, while younger people could be getting more exposed to new carcinogens, likely via their environment or diet, the scientists said. The new findings, the researchers said, emphasised the need for tailored research exploring causes of cancer subtypes in different age groups. “These findings can help inform future research and clinical and public health guidelines,” they wrote.
