Sacral and Rectal Necrosis after Carbon Ion Radiotherapy Reconstructed with Transpelvic Rectus Abdominis Flap

Carbon ion radiotherapy (CIRT) has been used for malignant tumors that are difficult to excise surgically, such as sacral chordoma, and the success of its outcomes is attributable to the high dose concentration and biological effects. CIRT has produced successful clinical outcomes, and it is considered to have fewer adverse effects on surrounding normal tissues; moreover, complications have been rarely reported. We describe a 75-year-old woman with a full-thickness sacral defect, who had received CIRT for sacral chordoma 3 years earlier. Computed tomography showed sacral bone destruction, and a colonoscopy revealed rectal necrosis. Rectectomy in addition to sacral bone resection was necessary, which resulted in a huge sacral defect of slightly anxious viability. We performed reconstruction of the sacral defect by using pedicled vertical rectus abdominis myocutaneous (VRAM) flap, obliterating sacral defects and intrapelvic dead space that occurred after rectectomy. Six months after surgery, the wound had healed well, and no complication was observed. Sacral complications after CIRT may affect surrounding normal tissues such as the rectum, and it would be difficult to reconstruct the resulting complications. The vertical rectus abdominis myocutaneous flap is considered useful for the simultaneous obliteration of sacral defects and intrapelvic dead space after CIRT.