What Causes PPB?

Unfortunately the cause for PPB is not known. As with most childhood cancers, PPB cases appear “out of the blue” with no clue as to why. Some of the basic research of the PPB Registry is aimed at trying to understand “why”, but as yet it is still completely unknown. There is nothing we could suggest to families that would have helped them avoid this diagnosis in their child.

There is a connection between “cysts” (larger-than-normal air-filled spaces) in the lung and the later development of PPB in these spaces. The reason such spaces are slightly prone to development of PPB is unknown. The most accurate thing we can say is that the cysts represent some type of abnormal formation of the lung tissue and this abnormality probably predisposes the tissue to becoming cancerous at a later date. On the other hand, many children have lung cysts without ever developing PPB. This problem raises questions for physicians and families about how to treat children with lung cysts, and there is no consensus on this issue.

In 25% of PPB cases, there are other children or young people in the family who have some kind of medical abnormality, including cancer [Registry Publications]. In such families we believe there is some genetic susceptibility to cancer and other abnormalities. However, even in these families, many children are normal, and we do not know the specific reason why the diseases occur in some of the children.