A guide to reactive oxygen species in tumour hypoxia: measurement and therapeutic implications.

Reactive oxygen species (ROS) are a diverse group of molecules that serve as both essential signalling mediators and potential drivers of oxidative stress. In tumours, ROS influence critical processes such as proliferation, angiogenesis, metabolic adaptation and therapy resistance. These processes are further modulated by reduced oxygen availability (hypoxia), a defining feature of many solid tumours that can alter redox balance and cellular signalling. The interplay between ROS and hypoxia is highly dynamic, with both factors shaping tumour behaviour in complex and often unpredictable ways. Accurately measuring ROS and tumour oxygenation remains a significant challenge due to their transient nature and variability in levels across different tumour types. In this guide, we provide a comprehensive update on the dynamic interaction between ROS and hypoxia in tumours, evaluate current strategies for ROS detection and discuss emerging therapeutic approaches that target redox vulnerabilities in cancer. Understanding the intricate relationship between ROS and hypoxia is crucial for refining therapeutic strategies and improving patient outcomes.