Table 1 Main cancer causes apart from that mentioned in Peto’s paradox

Genetic predisposition: heritable mutations that confer a higher cancer risk, for instance mutations in BRCA1 and 2 genes associated with 40–60 % cumulative risk of breast cancer [104].

Pathogens: some infectious agents like viruses, helminthes or bacteria could also trigger tumor development. For instance, schistosomes have been shown to induce bladder cancer, Human Papilloma Virus is associated with cervical cancer or Helicobacter pylori (bacteria) increases the risk of stomach cancer [87].

Pollutants: Pesticides, smoking or electromagnetic radiation are associated with increased risk of cancer [105]. A study conducted by the American Cancer Society shows that an increase of 10 micrograms per cubic meter of fine particles in suspension would potentially cause an 8–14 % increase of lung cancer cases [106].

Alimentation: There is a positive correlation between obesity and cancer mortality [107]. In fact obese people secret more leptine, a hormone which in vitro stimulates cancer cell proliferation [108].