So has anyone heard of post radiation non-cancerous cysts at or near the site of the first lesion? Would scar tissue show up as a cyst? Is this something common / semi common post treatment? We just can�t stop worrying and there doesn�t seem to be anything else we can actually do now since his last CT/ PET scan was just done on 5/14/09 and this cyst did not light up as cancer. Is it likely to become another cancer? Just so frightening. Thank you.