ベバシズマブはパクリタキセルとの併用でHER2陰性の進行・再発乳癌に対する有効性が示されており，無増悪生存期間を有意に延長させる．しかし，ベバシズマブ特有の有害事象も報告されており，投与の際には注意を要する．今回，再発乳癌に対しベバシズマブを使用し，腸管穿孔を起こした１例を経験した．症例は72歳女性．右乳癌術後５年目に多発リンパ節，肺転移を認め，化学療法で治療中に８次治療としてベバシズマブとパクリタキセル（BP）療法を開始した．１年ほど奏効したが，突然，腹痛を訴え受診した．CT で腹腔内にfree air を認めたため緊急開腹術を施行した．小腸に１か所の穿孔部位を認めた．病理組織検査では，穿孔部に乳癌の転移巣が認められた．乳癌に対するベバシズマブ併用化学療法中の消化管穿孔は報告が少ない．腹膜播種を認める症例やベバシズマブ投与期間の長い患者では，腹部膨満感や腹痛を訴えた際は消化管穿孔を念頭におく必要がある． Combination therapy with bevacizumab and paclitaxel (BP therapy) has been reported to be effective for the treatment of HER2-negative metastatic breast cancer and to significantly prolong progression-free survival. However, there are specific adverse effects induced by bevacizumab that physicians should pay attention to. We report a recent case of metastatic breast cancer with gastrointestinal perforation during bevacizumab therapy. A 72-year-old female patient had metastases into multiple lymph nodes and lungs five years after surgery for primary breast cancer, and was treated with several chemotherapies. The patient received BP therapy as the eighth treatment regimen. Although the therapy led to stable disease for approximately one year, the patient suddenly developed abdominal pain. Emergency laparotomy was performed because computed tomography revealed free air in the peritoneal cavity. A perforated lesion was found in her small intestine. On pathological examination, breast cancer metastasis was noted around the perforated site. There are few reports of gastrointestinal perforation during bevacizumab therapy for patients with metastatic breast cancer. When a patient has peritoneal dissemination, long-term BP therapy and abdominal pain, physicians should keep in mind the possibility of gastrointestinal perforation during BP therapy. (187 words
