The third paragraph: > To clarify, several cancers can be caused by infectious entities; cervical cancer, for example, is the work of HPV, a sexually transmitt

The third paragraph: > 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. Put another way, HPV is a virus whose effects can cause cancer. That is, it causes mutations in _your own_ cells that cause them to become cancerous. CTVT is essentially a parasitic cell line — not your cells hopping a ride on you.