As many of the organs at highest risk of tumour development in MEN1 syndrome such as duodenum, pancreas and lungs (bronchial carcinoids) are not suitable for preventive ablative surgery, routine surveillance of asymptomatic MEN1 at-risk individuals by biochemical analysis and imaging procedures (beginning in early childhood and continuing for life) is recommended. This evidence concerns the gene MEN1 and multiple endocrine neoplasia type 1.