This study is a multicentre, prospective, randomised non-inferiority trial nested within the OPTIMAL study. The OPTIMAL study is the backbone of the (OPTIMAL-) PORT study, encompassing the prospective cohort and providing the infrastructure for collection patient reported outcome measures. If patients do not have an indication for surgery, they can only be included in the OPTIMAL study. If patients have an indication for surgery, they are recruited for the OPTIMAL-PORT study. However, if patients do not give consent for randomisation for radiotherapy, they can give partial consent and participate in the prospective cohort and complete questionnaires. This data will contribute to the OPTIMAL study. Details concerning the OPTIMAL study are described in the respective protocol.