Although epidemiological studies overall found no association for IGF‐1, a reduced risk of lung cancer is reported with higher circulating levels of IGFBP‐3, when comparing the highest quartile versus lowest quartile of IGFBP‐3 in a Chinese prospective study (OR: 0.50, 95% CI: 0.25–1.02) 55. Here, IGF1 is linked to lung cancer.