An applicator for facilitating radiation treatment in a body cavity, particularly post resection, provides for superior wound closure management, with an integrated drain and a flexible main shaft that permits further treatments at intervals without disturbing the wound closure. The drain includes channels in the shaft, and the surface of an expandable balloon of the applicator may have features that help channel the flow of drain liquids toward the cavity entrance. Non-spherical, irregular geometries of balloons are achieved in several different ways. In some embodiments multiple balloons are included, either an inner and outer balloon or a series of balloons extending outwardly from the main shaft. Non-balloon applicators are also disclosed.