Cancer Causes: Genetic Mutations, Environmental Carcinogens, Lifestyle, and Immune Factors

Cancer arises from accumulated mutations in genes controlling cell growth, division, and death. Etiology is multifactorial:

1. Genetic Mutations

• Inherited (germline): BRCA1/2, TP53 (Li‑Fraumeni), APC (FAP), mismatch‑repair genes (Lynch).
• Acquired (somatic): Driver mutations from replication errors or mutagen exposure.

2. Environmental Carcinogens

• Tobacco smoke (PAHs, nitrosamines) → lung, bladder, pancreas.
• Asbestos → mesothelioma.
• UV radiation → melanoma, NMSC.
• Benzene → leukemia.
• Aflatoxin → hepatocellular carcinoma.
• Oncogenic viruses: HPV (cervical, oropharyngeal), HBV/HCV (HCC), EBV (lymphoma/nasopharyngeal), HIV (Kaposi sarcoma).

3. Lifestyle Factors

• Diet: processed/red meat, low fiber → colorectal.
• Alcohol → breast, esophageal, liver.
• Physical inactivity, obesity → 13 cancer types.

4. Immune Dysfunction

Immunosuppression (HIV, transplant, autoimmune therapy) impairs tumor surveillance → higher incidence of virus‑associated and skin cancers.

Prevention

~40% of cancers are preventable: tobacco avoidance, vaccination (HPV, HBV), healthy weight, diet, alcohol moderation, sun protection, screening.