We also found a persistent decrease in the plasma ghrelin levels within the weight-regain mice post-cancer cell implantation (day 35), in contrast to low-BMI control mice, which showed a significant increase in plasma ghrelin levels during metastatic outgrowth (Fig. 5E), suggesting that low BMI is a severe but modifiable risk factor for brain metastasis in lung cancer. This evidence concerns the gene GHRL and lung cancer.