The Connection Between Obesity, Breast Cancer and Lung Cancer
Research published in Nature Cell Biology investigated a specific potential pathway by which obesity may increase the risk for breast cancer progression and metastasis (development of secondary malignant growths at a distance from the primary site of cancer).
It is well known that obesity is associated with chronic, low-grade inflammation, which can disrupt homeostasis within the body via metabolic and endocrine-related means. The researchers chose to investigate the correlation between breast cancer and obesity to see if systemic inflammation has an explicit part to play in metastatic progression.
The team found that obesity significantly increases lung tissue neutrophil activity among mice as well as during human models. Neutrophils are white blood cells that usually respond to a bacterial infection and are also increased during any acute tissue inflammatory response. This finding suggests neutrophils will also respond to the systemic inflammation associated with obesity.
Interestingly, the data showed increased neutrophil activity in the lungs has synergistic effects on other immune “activators” including granulocytes, macrophages, and the cytokine interleukin-5 (IL5) associated with asthma. Their presence translates to increased breast cancer metastasis. The close distance and physiological connection between the breasts and lungs unfortunately allows for efficient spreading of the cancer.
Importantly, the study demonstrated weight loss to be sufficient in reversing this risk as it reduces serum levels of the immune activators mentioned above. The study suggests special considerations are needed among the obese breast cancer patient population to effectively manage cancer progression.
Quail, D.F., Olson, O.C., Bhardwaj, P., et al. (2017). Obesity alters the lung myeloid cell landscape to enhance breast cancer metastasis through IL5 and GM-CSF. Nature Cell Biology. 19. 974-987.