A certain type of treatment for kidney cancer causes high blood pressure in many patients.
The Vascular Endothelial Growth Factor (VEGF) pathway is a chemical signal produced by cells that stimulates the growth of new blood vessels. It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate. Solid cancers cannot grow beyond a limited size without an adequate blood supply, but if the cancer can express VEGF, it can grow and metastasize. One therapy to treat renal kidney cancer, or renal cell carcinoma (RCC), involves using agents (like sunitinib, sorafenib, bevacizumab, axitinib or tivozanib) that target the VEGF pathway to stop metastasization. The only problem is that one treatment side-effect is hypertension.
VEGF-targeted therapy is more specific than traditional chemotherapy and causes fewer side effects. However, a study has shown that it causes high blood pressure in 30-80 percent of patients. On the flip-side, due to the nature of hypertension, its manifestation is regarded as an important biomarker for response to the treatment. In other words, those RCC patients treated with VEGF-targeted therapy are likely to develop hypertension, but it also means that their bodies are responding to the treatment.
A study by Manuela Schmidinger, MD, medical oncologist, Medical University of Vienna, and Prof Alain Ravaud, Department of Medical Oncology, Saint-André Hospital, France, says that the way the treatment causes hypertension is not fully understood, but a main causes might be impaired angiogenesis (the excessive growth of new capillary blood vessels in the body) potentially involving generalized dysfunction of the microcirculation (blood circulation in the smallest blood vessels). Also, it could be the activation of the endothelin-1 system, suppression of the renin-angiotensin system, inhibition of endothelial nitric oxide synthase and increased vascular stiffness.
During the 2013 European Cancer Congress, Schmidinger discussed the mechanism and management of side-effects from targeted agents in VEGF inhibiting agents, including hypertension, diarrhea, and hand-foot syndrome. She said that it is crucial for treating physicians to appropriately inform patients prior to treatment that they need to obtain blood pressure readings three times a day during the first three months. Their blood pressure should also be corrected according to guidelines.