The purpose of this study is to identify in a prospective manner microregional profiles of oxygenation and proliferation based on exogenous and endogenous markers that are predictive for outcome of radiotherapy in squamous cell carcinoma of the larynx and to investigate if these profiles can identify patients that are most likely to benefit from hypoxia modifying treatment strategies like ARCON (Accelerated radiotherapy combined with carbogen breathing and nicotinamide).