The article addresses this: >To clarify, several cancers can be caused by infectious entities; cervical cancer, for example, is the work of HPV, a sexually tra

The article addresses this: >To clarify, several cancers can be caused by infectious entities; cervical cancer, for example, is the work of HPV, a sexually transmitted virus. But in those cases, the cancer itself is not infectious and cannot spread. CTVT is different: Each cancer cell is a free-living parasite that can set up another tumor on another dog. HPV can also (rarely) cause cancers of the throat and penis.