Specifically, Niu et al. reliably stated that circulating leptin levels are different among several population groups from low to high as follows: healthy people < breast benign disease patients < breast cancer patients < lymph node metastasis-positive patients, suggesting that the assessment of leptin levels should be considered as a suitable diagnostic tool in this neoplasia. The gene discussed is LEP; the disease is metastatic malignant neoplasm in the lymph nodes.