An endoscopic treatment system for use with an endoscope having a proximal end and a distal end and a longitudinal axis extending therebetween, the endoscopic treatment system comprising: a) a distal cap assembly having an end effector rotatable on an axis between open and closed positions, the end effector having a free end; b) a transmission assembly having proximal and distal ends, the distal end operably coupled to the end effector such that displacement of at least a portion of the transmission assembly rotates the end effector between the open and closed positions; c) a proximal handle assembly coupled to the transmission assembly and adapted to effect the displacement of at least a portion of the transmission assembly to rotate the end effector; d) a first lumen and a second lumen extending external to the endoscope from the cap assembly to the proximal handle assembly for receiving instruments therethrough, the first lumen in alignment with the free end of the end effector when the end effector is in the closed position, and the second lumen positioned between the first lumen and the transmission assembly; according to a first alternative of the endoscopic treatment system: e) a peripheral engagement structure (90, 290) adapted to be positioned about greater than 180° of a circumference of the distal end of the endoscope, the peripheral engagement structure (90, 290) being in an abutting relationship with a proximal end of the cap assembly; and f) a plurality of spaced apart ancillary clips, the ancillary clips adapted to retain the transmission assembly and the first and second lumen (34, 36) relative to the endoscope; or according to a second alternative of the endoscopic treatment system: f) a plurality of clips spaced apart along the transmission assembly and first and second lumen (34, 36), the clips each having a body adapted to extend greater than 180° about a circumference of the endoscope, the clips defining slots filled with a material having a higher coefficient of friction than the body; or according to a third alternative of the endoscopic treatment system: e) a peripheral engagement structure (90, 290) adapted to be positioned about greater than 180° of a circumference of the distal end of the endoscope, the peripheral engagement structure (90, 290) integrated with the cap assembly. a) a distal cap assembly having an end effector rotatable on an axis between open and closed positions, the end effector having a free end; b) a transmission assembly having proximal and distal ends, the distal end operably coupled to the end effector such that displacement of at least a portion of the transmission assembly rotates the end effector between the open and closed positions; c) a proximal handle assembly coupled to the transmission assembly and adapted to effect the displacement of at least a portion of the transmission assembly to rotate the end effector; d) a first lumen and a second lumen extending external to the endoscope from the cap assembly to the proximal handle assembly for receiving instruments therethrough, the first lumen in alignment with the free end of the end effector when the end effector is in the closed position, and the second lumen positioned between the first lumen and the transmission assembly; according to a first alternative of the endoscopic treatment system: e) a peripheral engagement structure (90, 290) adapted to be positioned about greater than 180° of a circumference of the distal end of the endoscope, the peripheral engagement structure (90, 290) being in an abutting relationship with a proximal end of the cap assembly; and f) a plurality of spaced apart ancillary clips, the ancillary clips adapted to retain the transmission assembly and the first and second lumen (34, 36) relative to the endoscope; e) a peripheral engagement structure (90, 290) adapted to be positioned about greater than 180° of a circumference of the distal end of the endoscope, the peripheral engagement structure (90, 290) being in an abutting relationship with a proximal end of the cap assembly; and f) a plurality of spaced apart ancillary clips, the ancillary clips adapted to retain the transmission assembly and the first and second lumen (34, 36) relative to the endoscope; or according to a second alternative of the endoscopic treatment system: f) a plurality of clips spaced apart along the transmission assembly and first and second lumen (34, 36), the clips each having a body adapted to extend greater than 180° about a circumference of the endoscope, the clips defining slots filled with a material having a higher coefficient of friction than the body; or according to a third alternative of the endoscopic treatment system: e) a peripheral engagement structure (90, 290) adapted to be positioned about greater than 180° of a circumference of the distal end of the endoscope, the peripheral engagement structure (90, 290) integrated with the cap assembly. f) a plurality of clips spaced apart along the transmission assembly and first and second lumen (34, 36), the clips each having a body adapted to extend greater than 180° about a circumference of the endoscope, the clips defining slots filled with a material having a higher coefficient of friction than the body; or according to a third alternative of the endoscopic treatment system: e) a peripheral engagement structure (90, 290) adapted to be positioned about greater than 180° of a circumference of the distal end of the endoscope, the peripheral engagement structure (90, 290) integrated with the cap assembly.