A condition marked by a side-to-side curve of the backbone. The curve is usually shaped like an S or a C. In most cases, the cause of scoliosis is not known. In some cases, scoliosis may be present at birth or it may be caused by muscle spasms, inflammation, tumors, or certain other disorders. It may also occur at some point in time after radiation therapy to the backbone.
Source: NCI Dictionary of Cancer Terms2012-06-13