Scientists from Australia noticed decreased levels of circulating cancer-associated protein biomarkers after bariatric surgery in obese patients. Many scientific studies proved that there is an association between obesity and risk of cancer development.
In the UK, obesity is considered to be the second (after smoking) most important avoidable risk factor for cancer. In the majority of studies obesity has a great impact on development of endometrial cancer, kidney cancer and hepatobiliary cancer. It does not affect lung cancer (the major risk factor is smoking), melanoma (the influence of UV is dominant) and brain cancer (the brain is anatomically shielded by blood-brain barrier from metabolic fluctuations caused by obesity). Despite many studies, exact molecular mechanisms that link obesity with cancer are still unknown. It is suggested that obesity can play a role in the initiation of carcinogenesis, because of mutagenic impact of reactive oxygen species on DNA. It is also possible that obesity contributes to promotion of carcinogenesis through alterations in the availability of nutrients and growth factors that are important for tumour growth. Another theory suggest that state of chronic inflammation caused by obesity can play a role in initiation or promotion of carcinogenesis.
Scientists from University of Notre Dame in Sydney recruited to their study 15 patients (8 male and 7 female) aged> 18 years old, with BMI> 30 kg/m2 with obesity comorbid illness or BMI>40 kg/m2. Everybody with past or present history of benign or malignant tumor or an inflammatory or autoimmune disorder was excluded. Another exclusion criterion was regular use of anti-inflammatory or corticosteroid medications.
All patients underwent laparoscopic sleeve gastrectomy (surgical procedure in which the stomach is reduced). Blood samples were collected from each patient before the surgery and 12 weeks after the surgery. In both blood samples concentrations of 34 biomarkers associated with the development of cancer in humans (sEGFR, FGF, follistatin, G-CSF, HGF, sHER-2, sIL-6Rα, leptin, osteopontin, PECAM-1, PDGF-AB/BB, prolactin, SCF, sTIE-2, sVEGFR-1, sVEGFR-2, angiopoietin, sCD40L, EGF, endoglin, sFASL, HB-EGF, IGFBP-1, IL-6, IL-8, IL-18, PAI-1, PLGF, TGFα, TNF-α, uPA, VEGF-A, VEGF-C, VEGF-D) were measured.
12 weeks after the surgery mean weight loss was 20.25 kg and mean BMI loss was 7,0 kg/m2. Levels of all biomarkers decreased, however significant reductions were observed for 17 of the 34 biomarkers. Statistically significant (p<0,1) decrease was observed in all of the VEGF family factors (VEGF-A, VEGF-C, VEGF-D, PLGF) and endoglin, that play a role in process of angiogenesis; in proinflammatory factors: IL-6, IL-8, IL-18, TNFα, PAI-1, sCD40L, sFASL; in epidermal growth factor family: EGF, TGFα (their expression worsens prognosis and and increases the metastatic potential of breast, renal, and colorectal cancers), HB-EGF; factors associated with obesity and insulin resistance: IGFBP-1 and prolactin.
Those results may contribute to exploring exact molecular mechanisms that link obesity with higher risk of cancer development. At the same time, they suggest that bariatric surgeries can make effective prevention of cancer in obese patients. Perhaps, in the future bariatric surgeries will be considered as a preventive action for cancer in obese patients. Nevertheless, further studies are required.
Written by: Magdalena Rejmak, Karolina Lewczuk
1) Farey, J.E., Fisher, O.M., Levert-Mignon, A.J. et al., Decreased Levels of Circulating Cancer-Associated Protein Biomarkers Following Bariatric Surgery. OBES SURG (2016). doi:10.1007/s11695-016-2321-y
2) Mazzarella L. Why does obesity promote cancer? Epidemiology, biology, and open questions. Ecancermedicalscience. 2015;9 doi: 10.3332/ecancer.2015.554.
3) Parkin DM, Boyd L, Walker LC. The fraction of cancer attributable to lifestyle and environmental factors in the UK in 2010. Br J Cancer. 2011;105(Suppl 2):S77–S81. doi: 10.1038/bjc.2011.489
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