Table 1.
Summary of selected clinical studies that recorded a positive association between overexpression of leptin and/or its receptor proteins in tumor tissue and cancer cell invasion or metastasis
| Site | Subjects | Findings | Investigators |
|---|---|---|---|
| Breast | 76 invasive ductal carcinomas and 32 normal control samples. | Distant metastasis was detected in 21 (34%) of 61 Ob-R-positive tumors with leptin overexpression, but in none of the 15 tumors that lacked Ob-R expression or leptin overexpression. | Ishikawa et al. 2004 [104] |
| Colon | 68 cases of colorectal carcinoma tissue, tumor adjacent tissue and normal colorectal tissue. | Expression of leptin and Ob-R in tumor was correlated with depth of bowel wall invasion, lymph node metastasis, and distant metastasis. | Liu et al. 2011 [117] |
| Colon | 108 patients with colorectal carcinoma. | Leptin/Ob-R expression was significantly associated with TNM stage, lymph node metastasis, and distant metastasis. | Wang et al. 2012 [116] |
| Esophagus | 122 cases of esophageal squamous cell carcinoma and 40 normal esophageal mucosa tissue. | Expression of leptin was significantly correlated with lymph node involvement and advanced tumor stage. | Duan et al. 2014 [102] |
| Lung | 50 patients with lung cancer along with another 50 lung cancer patients with metastatic bone lesions. | Leptin was present at higher levels in bone metastasis cases. | Feng et al. 2013 [14] |
| Ovary | 70 ovarian cancer cases. | Ob-Rb was highly overexpressed in metastases compared to primary tumors. | Kato et al. 2015 [16] |
| Pancreas | 60 pancreatic cancer tissue specimens. | Expression of Ob-Rb was significantly stronger in patients with lymph node metastasis than in those without lymph node metastasis. | Fan et al. 2015 [90] |
| Stomach | 343 cases of gastric carcinoma. | Ob-R expression was correlated with poor survival in 207 patients with advanced gastric cancer (muscle or deeper invasion), 139 of the Lauren diffuse group (poorly differentiated tumor cells scatter throughout the organ), and in 160 patients with lymph node metastasis. | Choi et al. 2015 [103] |
| Stomach | 84 cases from primary gastric carcinoma. | Moderate to strong immnoreactivity for leptin was identified in 57% (n=48) cases. Leptin was positively correlated with lymph node metastasis and clinical stage. | Dong et al. 2014 [109] |
| Stomach | 110 gastric cancer specimens and 96 normal gastric mucosa were analyzed. | Expression of leptin was associated with tumor invasion depth, lymph node metastasis, and expression of HER2 and VEGF. | Geng et al. 2012 [106] |
| Stomach | 207 gastric carcinomas (100 early and 107 advanced carcinomas) | Expression levels of both leptin and Ob-R tended to increase as the depth of tumor invasion or TNM stage increased. | Ishikawa et al. 2006 [107] |
| Stomach | 61 gastric cancer specimens. | Leptin expression was significantly associated with lymph node metastasis and higher stage. | Zhao et al. 2007 [105] |
| Thyroid | 49 papillary thyroid carcinomas. | Coexpression of leptin and Ob-R in primary neoplasms had greater incidence of lymph node metastasis. | Cheng et al. 2010 [95] |
| Thyroid | 93 cases with papillary thyroid carcinoma and 25 cases with medullary thyroid carcinoma. | For papillary thyroid carcinoma, expression of leptin and Ob-R was significantly correlated with lymph node metastasis and advanced stage. For medullary thyroid carcinoma, Ob-R was significantly correlated with lymph node metastasis and advanced stage. | Fan and Li 2015 [93] |