David G. Symeonidis was born in Athens and in 2007 he was admitted to the School of Medicine of the National and Kapodistrian University of Athens through nationwide exams where he graduated in 2013 with honors. He served in the Navy as a military base physician and then completed his Oncology residency at Tzaneio General hospital and Metaxa Memorial Cancer Institute.

In 2016, he received the title of postgraduate studies from the University of Athens with the title Neoplastic Disease in Man. Subsequently, in 2020, he completed and received the title of Doctor of Philosophy from the Medical School of Athens for the doctoral thesis concerning cancer stem cells in patients with colon cancer.

In 2021, he was recognized through official evaluation exams as excellent of the European Society of Oncology, while he is a member of the Hellenic and American Society of Oncology.

He constantly attends Greek and international seminars, he is often a speaker at conferences in Greece and abroad. He has numerous publications (researchgate) in Greek and international journals, while he has participated in clinical studies whose findings are presented at European and global conferences.

He monthly publishes  articles on websites and media on topics related to neoplastic disease, while at the same time he has a presence on television programs for medical information.

From 2022 he is consultant, in the 2nd Oncology department at the Metropolitan General Hospital, while he owns private clinics in Piraeus and Argolis (Peloponnese).