The unknowns surrounding the mysterious rise of cancer in young adults

Environmental and Chemical Exposures

• Some suggest “forever chemicals” (PFAS), microplastics, and plastic-packaging contaminants as contributors, but note that hard human evidence is limited or “not seen yet.”
• Others point to pesticides and herbicides (especially glyphosate), though counter‑comments argue rising celiac diagnoses could be better explained by awareness and testing.
• Emulsifiers in processed/“low‑fat” foods are raised as another possible factor, with at least one linked epidemiological paper.
• Climate change is mentioned once, more as a rhetorical point than a developed argument.

Diet, Obesity, and Processed Foods

• The cited BMJ Oncology study lists diet, alcohol, and tobacco as main early‑onset cancer risks.
• Multiple comments suspect ultra‑processed foods, sugary drinks, and low fiber intake, especially among younger people.
• Obesity is repeatedly connected to cancer risk; mechanisms are debated and not fully resolved in the thread.

Physical Activity and Cancer Mechanisms

• Many comments emphasize that exercise reduces cancer risk, even if mechanisms are complex.
• Proposed mechanisms include: improved immune surveillance, reduced chronic inflammation, hormetic stress and repair, better toxin clearance via circulation, effects on cancer metabolism (e.g., lactate/Warburg effect).
• Some skepticism arises about simple “more immune activity is always better” stories; biology is described as interdependent and messy.

Tobacco, Alcohol, Vaping, and Other Substances

• While traditional smoking and drinking have declined in younger cohorts, binge drinking and vaping are seen as rising.
• Vaping and marijuana are generally viewed in the thread as likely less harmful than cigarettes and heavy alcohol, but with disagreement and highlighted gaps in long‑term data.
• Energy drinks and heavily marketed “kid drinks” are mentioned as a possible, but unsubstantiated, risk factor.

COVID-19, Vaccines, and Immune Dysregulation

• Several comments speculate that SARS‑CoV‑2 infection may promote cancer or exhaust cancer‑fighting immune cells, linking to early studies.
• Others raise mRNA vaccines, spike protein, pseudouridine, and dysautonomia as potential contributors, often in strongly worded, conspiratorial ways.
• No consensus emerges; some emphasize that the main cancer trend data cited stops at 2019, i.e., pre‑pandemic, making firm links to COVID or vaccines unclear.

Data Quality, Studies, and Anecdotes

• One commenter notes a past misconduct finding involving an author of the BMJ Oncology paper and urges caution in interpretation.
• Several highlight that cancer latency can be decades, so recent behavior changes (including the pandemic) may not yet fully show up.
• Personal anecdotes (heavy smokers with no cancer, etc.) are explicitly criticized as statistically misleading.
• There is repeated emphasis on the need for large, prospective lifetime cohort studies and better pre/post‑COVID and cross‑country comparisons.

Other Speculated Factors

• Ideas mentioned with little supporting detail include: increased sedentary lifestyles, higher maternal age and stress due to expanded higher education, poorer sleep, depression, and widespread exposure to low‑quality imported consumer goods.
• These are presented as hypotheses rather than established causes.