Rising Colorectal Cancers in Young Adults Spark Questions A recent paper in JAMA confirms a troubling trend: colorectal and other cancers are increasing among adults under 50. The study highlights that incidences of 14 cancer types—including colorectal and breast cancer—are rising within this younger demographic. While the paper remains cautious about speculation, it underscores the urgency to investigate causes beyond enhanced diagnostic screening. Screening vs. True Rise in Incidence Some argue increased screening explains the uptick, but data suggests otherwise. The American Cancer Society and global surveillance note that early-onset colorectal cancers are often diagnosed only after symptoms, indicating real increases . In the UK, the 2024 National Bowel Cancer Audit reported 35,779 new diagnoses in 2021–22, rising to 38,604 in 2022–23—an almost 8% year-over-year jump. Importantly, rates rebounded quickly to pre-pandemic levels by October 2020, with sustained rises from April 2021—coinciding with widespread mRNA COVID-19 vaccine rollout. Global Context and the Search for Roots Worldwide reports echo these patterns: one cohort of 562,145 patients in the US between 2010–19 found significant increases in early-onset cancers. In Europe, colorectal cancer among those under 50 rose dramatically, with annual increases of 7.9% for ages 20–29 and 4.9% for 30–39. Dietary shifts, microbiome alterations, obesity, and ultra-processed food intake are widely discussed potential drivers. But a full understanding remains elusive. Could mRNA Vaccines Play a Role? A key question arises: might mRNA vaccines contribute etiologically to colorectal cancer? Association alone does not prove causation. Yet under Bradford Hill’s criteria—consistency, temporality, dose–response, biological plausibility—it’s worth exploring possible mechanisms. DNA Integration from mRNA and Viral Contaminants Laboratory evidence shows SARS‑CoV‑2 mRNA can be reverse-transcribed into DNA within human cells (e.g., liver cell lines). There’s theoretical potential for integration into the host genome, possibly disrupting tumor suppressor genes or activating oncogenes. Additionally, studies have reported presence of SV40 DNA in vaccine lots, which could inactivate tumor suppressor genes like p53 and RB, though definitive causal links are not yet established. Prolonged Spike Protein Expression One study detected vaccine-derived mRNA in patients up to 60 days post‑vaccination, and circulating spike protein persisted even longer. Modified nucleosides (pseudouridine) extend mRNA stability—raising the possibility of chronic spike protein production. Sustained expression can perpetuate inflammation, known to promote cancers (e.g., HPV‑related cervical or colitis-related colon cancers). Studies show lipid nanoparticle (LNP)-mRNA constructs can reach various organs beyond the injection site. If stem cells are affected, any genetic or epigenetic changes could propagate through progeny cells. Lipid Nanoparticle Distribution and Stem Cell Impact Preclinical data show that lipid nanoparticle (LNP)-mRNA constructs can reach various organs beyond the injection site. If stem cells are affected, any genetic or epigenetic changes could propagate through progeny cells. Though still theoretical, such effects demand investigation given the foundational role of stem cells in tissue renewal. Immune Dysregulation and Molecular Mimicry mRNA vaccines could provoke autoimmune reactions via molecular mimicry, where spike protein antibodies cross-react with host proteins. This may disturb immune regulation, including T‑regulator cell function, analogous to how chronic inflammation fosters tumor growth. What’s Missing and What’s Needed Data comparing vaccinated and unvaccinated populations on a national scale are lacking—and essential. If the number of vaccine doses correlates with cancer risk in a dose–response pattern, or if cancer increases precede vaccination drops (reversibility), Bradford Hill’s criteria could be satisfied decisively. At present, these links are theoretical but biologically plausible. More Studies Are Needed Immediately We need large-scale epidemiological studies—cross-country comparisons, time-trend analyses, and stratification by vaccine exposure. Release of granular patient data, including age, sex, vaccination history, and diagnosis timing, is critical. Without transparency, answers may only emerge decades later—as seen with past public health delays (e.g., the UK infected blood scandal). This is Urgent How much mRNA vaccines contribute to cancer, understanding the root causes of rising early-onset cancers is urgent. Even minor vaccine-related risks must be weighed against benefits. And if mechanisms like spike-induced inflammation or DNA integration are real, the implications would extend beyond COVID‑19 to the entire era of mRNA therapeutics.