Are uterine fibroids cancerous?

No: Fibroids themselves are tumors but not cancerous. However, once is a while a uterine cancer can appear similar to a fibroid and it is possible to believe that a woman has a fibroid when in fact there is actually a cancer present.

Very rarely: Only in very rare instances can fibroids be cancerous. If there is very rapid growth in the size, these are the ones that could be a leiomyosarcomas but again very rare.