Radioiodine (RAI) is the first theranostic to diagnose and treat cancer effectively. The article highlights the sequence of events of Dr Saul Hertz in establishing the medical uses of Iodine -131 (I-131). Dr Hertz overcame many challenges to bring his paradigm changing work to fruition. The discovery of the medical uses of RAI has created a profound and enduring legacy, as ushering in precision oncology.
Key words: Historic Vignette ,RAI ,Theranostics, Precision Oncology