Researchers from the Centres for Disease Control and Prevention (CDC) have made a startling discovery when investigating the death of a cancer sufferer. The group of scientists discovered that the patient’s strange tumours had initially developed as cancer cells within a tapeworm.
Dr Atis Muehlenbachs, lead author of the study, published in the New England Journal of Medicine, said: “We were amazed when we found this new type of disease – tapeworms growing inside a person essentially getting cancer that spreads to the person, causing tumours.”
The case arose when the tumours of a 41-year old HIV-positive man in Colombia. Unfortunately, the patient was too ill by the time doctors identified the tapeworm causing the tumours. He died three days later.
The worm tissue came from dwarf tapeworm – Hymenolepis nana. Dr Peter Olson, from the Natural History Museum, told the BBC: “There is something very special about this species. It is able to carry out its whole lifecycle in one host and that is absolutely unique.”
The worm, who spews out thousands of eggs into the gut of a human host every day, usually occupies a human host through food infected by rodent droppings or insects or, more commonly, by accidentally ingesting the faeces of another infected person. Rather than the worm getting cancer, it is thought that one of these eggs penetrated the lining of the intestines, mutated and ultimately became cancerous.
Dr Olson added: “They were dividing and proliferating out of control and that is really what defines a cancer so they had a tape worm tumour.”
Prof Mel Greaves, the director of the centre for evolution and cancer at The Institute of Cancer Research in London, told the BBC: “What is extraordinary is that it is free cells of the parasite growing and in a cancer-like fashion rather than whole tapeworms.
“Species from almost all invertebrate phyla can develop cancer and the potential seems inherent to animal cells, and particularly the stem cells of multicellular animals. What has transpired in this case is that an exceptional combination of circumstances permitted this potential to be expressed in a very foreign host.”