Contagious Cancer, Transplanted Organs, Pregnancy and the Abscopal Effect: Clues to a Cure?
A lethal contagious cancer is spreading across the population of Tasmanian devils, threatening the species with extinction in the wild. The animals appear to have no immunity to this transplanted foreign tissue, which aggressively progresses and takes their lives. In stark contrast, in dogs there is another contagious cancer which, after initial growth, typically rapidly regresses as the immune system rejects this foreign tissue.
In many ways, human cancers behave more like the Tasmanian devil situation - cancer is granted “privilege” from the immune system. Are there other situations in which immune privilege is granted and foreign tissue effectively evades the immune system? Pregnancy, as most strikingly demonstrated in surrogate motherhood, exhibits a similar phenomenon. Cancer seems to have usurped the secrets of the placenta that confer invisibility to the immune system. Further proof of this is seen in the rare clinical situations wherein a transplanted organ harbors an unknown malignancy.
Although transplanted organs are normally vigorously rejected when immunosuppression is ceased, cancers that might have tagged along for the ride within transplanted organs sometimes thrive unmolested. What clues can be gleaned from these fascinating observations that would allow clinicians to better manage human cancer? Is there some way to put all these clues together into a cohesive framework? Somewhat ironically, ionizing radiation via the abscopal phenomenon, could possibly provide a means of making human cancer behave more like the dog than like the devil.
Dr. James S. Welsh is the Medical Director of the NIU Institute for Neutron Therapy at Fermilab and an attending physician for Nuclear Oncology Medical Care. Dr. Welsh is board certified in radiation oncology and neuro-oncology. He did his graduate school training at Yale in Molecular Biophysics and Biochemistry and received his MD at SUNY Stony Brook. His residency training was at The Johns Hopkins Hospital and he remained on staff there as an Assistant Professor. He moved to the University of Wisconsin in Madison to participate in the initial clinical and preclinical investigations of helical tomotherapy and became Clinical Professor of Human Oncology and Medical Physics.
Before returning to the upper Midwest he was Professor of Neurosurgery and Radiology at LSU School of Medicine in Shreveport, Louisiana. He has been on the Advisory Committee on the Medical Uses of Isotopes (ACMUI) for the United States Nuclear Regulatory Commission for the past five years. He is currently on the Board of the American College of Radiation Oncology and is also a board member for Coqui Radioisotopes, a company that aims to manufacture medical isotopes domestically in the near future.