Can your child be born with a cancer already growing inside him?

Yes: This isn't very common, but some cancers begin growing while in utero. Benign taratomas are the most common sited, but malignant tumors have been recorded.

Yes: A few tumors, e.g. Teratomas, may be present at birth. Some childhood tumors that may present in a neonate could be presumed to have started before birth, e.g., neuroblastoma. Some vascular tumors. Though not cancerous, develop in utero and are present at birth.

While the incidence: Is tiny, lymphocytic leukemia, neuroblastoma, medulloblastoma, retinoblastoma and wilms can be present before birth. Some in-born errors in development are serious enough to cause incomplete development and in utero demise leading to spontaneous abortion (miscarriage to those not liking the medical term).