Mr Oikonomou is a consultant head and neck oncology surgeon who gained his MD from the University of Ioannina, Greece, in 2005, before becoming a military doctor in the Hellenic Army. He taught physiology at the 1st Vocational Training Institute (IEK) for 6 months and later undertook a fellowship in children's otolaryngology at the Children's Hospital Armand Trousseau in France. Here, he trained under the supervision of Professor Garabedian and gained expertise in children's otorhinolaryngology, head and neck surgery, and rare otorhinolaryngology diseases.

In 2015, he joined St George's University Hospital NHS Foundation Trust as a head and neck specialist registrar, where he undertook laryngeal, parotid, and thyroid surgery. He went on to work in skull base, otology, and voice surgery before becoming an advanced fellow in head and neck surgery. Following this, he spent a year as a senior clinical fellow in advanced head and neck surgery at Guy's and St Thomas' NHS Foundation Trust before joining Addenbrooke's Hospital.