Saul Hertz, M.D. (April 20, 1905 – July 28, 1950) was an American physician who devised the medical uses of radioactive iodine. Hertz pioneered the first targeted cancer therapies. Hertz is called the father of the field of theranostics, combining diagnostic imaging with therapy in a single or paired chemical substance(s).
Early life and education
Saul Hertz was born on April 20, 1905, to father Aaron Daniel (A.D.) Hertz and mother Bertha Hertz in Cleveland, Ohio. His parents were Jewish immigrants from what is currently Golub-Dobrzyń in Poland. A.D. Hertz was a successful real estate developer. The Hertz's raised their seven sons according to Orthodox traditions. Saul Hertz attended public school and went on to graduate from the University of Michigan with Phi Beta Kappa honors in 1924. He received his medical degree from Harvard Medical School in 1929, at a time when there were strict quotas for outsiders (particularly Jews and Catholics – there were no women). Hertz completed his internship and residency at Cleveland's Mount Sinai Hospital, which had been established to serve Cleveland's East side Jewish population.
Early studies with radioactive iodine
Hertz joined the Thyroid Clinic and Metabolism Laboratories at Massachusetts General Hospital in 1931. Although initially a volunteer, shortly thereafter, Hertz became Chief of the Thyroid Clinic, serving in this capacity from 1931-1943.
On November 12, 1936, Karl Compton, then president of the Massachusetts Institute of Technology, gave a presentation, entitled "What Physics Can Do For Biology and Medicine" in Harvard Medical School's Vanderbilt Hall. Hertz spontaneously asked President Compton, "Could iodine be made radioactive artificially?" on possible applications of physics to medicine. Compton responded in a letter to Hertz on December 15, 1936, writing, "Iodine could be made artificially radioactive" and "emits gamma rays and beta rays." On December 23, 1936, Hertz replied, “that iodine is selectively taken up by the thyroid” and “that he hopes that it will be a useful method of therapy.”
In 1937, Hertz began a collaboration with the physicist Arthur Roberts of the Massachusetts Institute of Technology (MIT). The purpose of the collaboration was to explore possible applications of iodine radioisotopes for diagnosis and treatment of thyroid diseases. Robley D. Evans, Director of the Radiation lab of MIT hired Arthur Roberts. As a condition of his employment, any papers forthcoming would include Robley Evans as an author. The Harvard Milton Fund sponsored the first preclinical studies of isotope iodine-128 on thyroid function in 48 rabbits, which Roberts produced without a cyclotron. Roberts produced the iodine-128 by means of neutron bombardment, building on previous studies by physicist Enrico Fermi. Roberts also devised a Geiger-Müller detector for quantifying the amount of the radioisotope of iodine present in the biological specimens produced in the experiment.
Hertz's experiment with Roberts involved studies of 48 rabbits. They determined in the study that the hyperplastic thyroid gland absorbed more of the radioactive substance than the normal gland. This proved that radioactive iodine could serve as a radioactive tracer in thyroid function. The tracer procedure was critical for determining the amount of iodine the human thyroid took up so that the dosage of radioactive iodine could be established for therapeutic purposes.
The original manuscript describing their rabbit study findings had Hertz and Roberts as the coauthors as they had done the work and written the paper. Primary sources document Roberts' production of I-128 at the MIT laboratory, while Hertz and Roberts solely administered and analyzed the biodistribution of the radioisotope in the rabbits. Robley Evans insisted that his name be added to the author list at the time the Hertz/Roberts study paper was published. Evans had taken no part in the research or writing of the paper.
At the time of the 1937 rabbit studies, Hertz predicted the therapeutic use of radioactive iodine for treating thyroid carcinoma in a medical journal.
Therapy with radioactive iodine
Hertz's initial studies were conducted with iodine-128. However, this isotope has a half-life of only 25 minutes, rendering it impractical as a therapeutic or diagnostic agent. Human application of the iodine radioisotopes required a more suitable radioisotope of iodine.