Altitude

Altitude should be framed carefully. Living or traveling at altitude is not an established direct cause of cancer. The cancer-related concept is hypoxia: low oxygen availability can activate cellular stress responses, blood-vessel signaling, inflammation, and metabolic adaptation. In established tumors, hypoxic regions are associated with aggressive behavior and treatment resistance. That does not mean ordinary altitude exposure initiates cancer. If this Cause is retained, it should describe altitude as an indirect oxygen-stress topic with uncertain population-level cancer relevance, not as a proven carcinogenic exposure.