In canine transmissible venereal tumour (CTVT), the cells of the tumour itself are transmitted between dogs. Scientists and vets at University College London (UCL) have traced the source of this cancer to a single wolf or dog that lived in China or Siberia more than 250 years ago.
Some human cancers such as cervical cancer may be considered to be 'catchable', as they are initiated by viruses transmitted between people – in the case of cervical cancer, by certain types of papilloma virus. What is unusual about CTVT in dogs, however, is that no virus is involved – the cancer itself is effectively passed on.
Forensic DNA tests were conducted on tumour tissues from 16 dogs affected by CTVT. The dogs were being treated for the cancer by vets in Italy, India and Kenya who provided the biopsies. Veterinarian researcher Dr Claudio Murgia found that in all cases, the tumours were genetically different from the affected dog – in other words, the cancer had come from a different dog.
A further analysis of 40 tumours archived in vet labs in five continents showed that the tumours were genetically almost identical and demonstrated that CTVT originally came from a single source and has since spread across the globe.
Professor Robin Weiss of the UCL Division of Infection and Immunity, who led the research team, says: “Our discovery is of much broader significance than simply a disease in dogs. Firstly, CTVT represents the longest-lived cancer 'clone' known to science. It contradicts the current view that cancer cells generate more and more mutations and inevitably become more aggressive if untreated.”
MEDICA.de; Source: University College London