In the field of cancer research, there has been a long-held belief that cancer, also known as a malignant tumor or neoplasm, is the result of the unregulated proliferation of cells that invade or spread to undesired parts of the body. Surely, such invasive cells originate from within a patient’s body and are not horizontally transferrable between patients (non-infectious and non-pandemic), not to mention between species. However, a recent case study reported by the CDC may change this view forever where the first case of a cross-species transfer of malignant cells has been recorded.
A case study released in the November 5 issue of the New England Journal of Medicine (NEJM) reported that a 41-year-old Columbian man infected with both HIV and dwarf tapeworm (Hymenolepis nana) had small tumor-like growths in lungs and lymph nodes. A follow-up diagnosis using pathological and genomic approaches revealed that the invasive, tumor-like structure was actually made of undifferentiated proliferating cells of tapeworm origin. This is the first time ever that a tumor of foreign origin has been reported to be developing inside the human body. Although the patient eventually died of renal failure, further analysis suggested that an HIV-compromised immune system is likely to be the main reason for the successful proliferation of tapeworm-origin tumor cells within his body.
This case report raises serious concerns as well as opportunities in the field of cancer-related research and development. Whilst such combination of HIV and tapeworm infections are indeed very rare, a similar compromised immune system are more commonly found in patients undergoing chemotherapy and/or radiotherapy treatments. Previously, most efforts have been devoted to develop a pathogen-free environment, such as germ-free chambers, for these patients.
The possibility of parasitic infections and the horizontal transfer of potential life-threatening tumors between a host and parasite has never been explored before this case. Since tapeworms infect an estimated 75 million people worldwide, it would be highly desired for healthcare and/or pharmaceutical enterprises to allocate appropriate attention as well as resources into this specific field of research.
Further Readings:
Malignant Transformation of Hymenlepis nana in a Human Host, Muehlenbachs et al., N Eng J Med 373:19, 1815-1852
Image credits and caption: Three adult specimens of the H. nana parasite, also known as dwarf tapeworm. CDC/Georgia Department of Public Health
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