ARE 9 BRADFORD HILL CRITERIA ENOUGH? CANCER IS VIRAL.

Cancer causes approximately 10 million deaths per year and is defined as multifactorial without a single recognized primary etiology. This analysis applies the 9 Bradford Hill criteria (1965) — the consolidated epidemiological standard for establishing causality — to the hypothesis that cancer is predominantly caused by latent viral pathogens.All 9 criteria are satisfied: strength of association (RR 2.21 in surgeons, RR 2.10 in transplant recipients, RR 1.83 breast cancer in oncology nurses); consistency (replicated across independent studies in multiple populations and countries); specificity (only virus-associated tumors increase in immunosuppressed transplant recipients: lymphoma 7.54x, hepatocarcinoma 11.56x); temporal precedence (HPV 10–15 years before cervical cancer; HBV/HCV 20–40 years before hepatocarcinoma); dose-response gradient (more indoor life = more cancer, replicated in 6 countries); biological plausibility (latent pathogen + biofilm + chronic silent inflammation → replicative DNA damage); coherence (consistent with 12 IARC Group 1 oncogenic viruses); analogy (H. pylori, HPV, HBV/HCV as validated models); and reversibility (HPV vaccine −88% cervical carcinomas; HBV/HCV antivirals reduce hepatocarcinoma incidence; leukodepletion reduces HHV-8 transmission to zero).Four additional convergent pieces of evidence are presented: cancer incidence approximately 100× lower in ancient Egypt; breast cancer risk RR 1.83 in oncology nurses (Ratner, 2010); 87% of lung cancer cases in Chinese non-smokers; increasing pediatric tumor incidence incompatible with the theory of randomly accumulated mutations.Alternative theories — genetic, environmental, and lifestyle — satisfy 4/9, 6/9, and 7/9 criteria respectively. The viral hypothesis satisfies the maximum available epidemiological standard.The hypothesis is falsifiable through ultra-deep metagenomics on 1,000 sporadic tumors: less than 20% positive → hypothesis falsified; more than 70% positive → infectious component historically underestimated. Implications concern prevention, diagnosis, therapy, and research.Cancer is predominantly viral. The authors of the cited studies have made a fundamental contribution to humanity's scientific knowledge. This work does not constitute a criticism of their efforts, but an attempt at a cross-disciplinary synthesis of independently produced evidence. Deep and sincere gratitude goes to all those who work every day on the front lines of cancer research. Thank you for your contribution.