When the original tumor extent is substantial (displaces normal abdominopelvic organs), but responds well to therapy (i.e. as of week 12) - How would you target the pretherapy extent without unnecessarily overtreating the previously displaced organs? 

i.e. Should your CTV1 encompass the current bladder tumor plus a 1 cm expansion w/o the displaced bowel volume, OR should it include the entire pre-chemotherapy bladder tumor extent (which necessitates irradiating large amounts of normal bowel)?

Are there potentially infiltrated spaces which should be covered beyond the 1cm expansion on the post-therapy extent which were likely involved pre-therapy?