Article by Adam Barsouk is an oncology fellow at Johns Hopkins University and author of Outsmarting Cancer: Risk Reduction and the Power of Prevention. His writing has been featured in The Wall Street Journal, Forbes, The Chicago Tribune, and more.
We are witnessing a quiet but growing medical crisis: the rapid, unexplained rise of early-onset cancers in adults under 50. Rates of cancer have doubled in the last thirty years for young adults. Colorectal cancer, once a rare diagnosis for anyone born after 1970, has become the leading cause of cancer death in this demographic, prompting doctors to recommend colonoscopies starting at age 45.
The statistics are as stark as they are confusing. Someone born in 1990 has double the risk of colon cancer and quadruple the risk of rectal cancer compared to someone born in 1950. Rates of pancreatic, stomach, breast, and even lung cancer among non-smokers are also inching upward in millennials and Gen Xers at an alarming pace.
The Biological Fire: Obesity and Inflammation
While we are a society obsessed with fat—eating it, burning it, and injecting drugs to melt it away—the real question isn’t just about fitting into smaller jeans, but whether we can stop this silent killer. After smoking, excess weight is now the second leading preventable cause of cancer worldwide. Approximately 5% of cancer diagnoses in men and 10% in women are attributable to obesity, and we are seeing a spike in obesity-related cancers in young adults.
To understand the stakes, we have to look at biology. Humans evolved to carry two to three times more fat than our closest primate relatives—a survival mechanism for enduring long periods of hunger. Today, that evolutionary advantage has become a liability. When fatty tissue expands too quickly, it outgrows its own blood supply, causing the oxygen-starved cells to undergo stress and die. This triggers the immune system’s “clean up crew,” sparking chronic inflammation.
This biological stress acts as an invisible fire, damaging healthy DNA and creating the perfect soil for tumours to take root. Years later, the fingerprints of that original inflammation are often found in spreading cancers; in breast cancer patients, for example, higher levels of inflammation in tissue correlate with a worse prognosis.
The GLP-1 Revolution and The “Birth Cohort” Mystery
Enter the GLP-1 agonists. Drugs like Wegovy and Ozempic have ushered in a new era, helping patients achieve 5-20% weight reduction by mimicking satiety hormones. For the first time in decades, the U.S. obesity rate has ticked downward, dropping from 40% to 37% in just three years. If these drugs can douse the inflammatory fire of obesity, they may well be the most powerful anti-cancer tool we have developed in years.
However, obesity alone cannot explain why marathon runners and health-conscious adults in their 30s and 40s are also facing advanced diagnoses. Scientists are looking for a “birth cohort effect”—a smoking gun hidden in the environment or lifestyle of the last 40 years. Suspects include the ubiquity of microplastics, changes in the gut microbiome caused by childhood antibiotic overuse, and the dominance of ultra-processed foods, which now make up roughly 70% of American diets. Research increasingly links these foods to cancer regardless of a person’s weight.
Systemic Solutions for a Systemic Problem
We cannot simply prescribe our way out of this crisis. GLP-1s are a modern solution to a modern problem; they treat the symptom, but they are expensive, require lifetime adherence, and do not fix a food system flooded with ultra-processed options.
Real prevention must happen upstream. This requires a multi-faceted approach:
- Food System Reform: We must revise school lunch menus to eliminate processed junk, incentivise grocery stores to open in food deserts, allow food stamps (SNAP) to cover hot, healthy meals, and tax ultra-caloric, ultra-processed foods. These interventions are far cheaper than a lifetime supply of GLP-1s and offer savings beyond the pharmacy counter.
- Healthcare Access: Medical research and public health cannot be partisan issues. Over 50% of these early deaths may be preventable. Medicaid and Obamacare insurance allow Americans to receive the health screenings and medications that catch cancer before it metastasises. Cuts to Medicaid eligibility and Obamacare subsidies will lead to millions of excess and preventable deaths, pouring gasoline on our burning cancer epidemic.
- Patient Advocacy: We must close the dangerous gap between perception and reality. Most young adults and their doctors brush off persistent symptoms—changes in bowel habits, fatigue, abdominal pain—believing they are “too young” for cancer, often misdiagnosing early warning signs as IBS or haemorrhoids.
Fat and food are healthy in balance, but our current lifestyle has tipped the scales toward inflammation and disease. GLP-1s have given us a fighting chance to reverse the trend, but they are not a magic bullet. To truly extinguish the risk of cancer, we need more than a syringe; we need a society that makes it easier to be healthy in the first place. The “old person’s disease” is now our disease, and we can no longer afford to wait until middle age to pay attention.
Read the first chapter of Dr Adam’s book ‘Outsmarting Cancer’.
Medical disclaimer
This content is for general information only and is not a substitute for professional medical advice. Always consult your GP or a qualified healthcare professional if you have any concerns about your health.