[Two cases of bowel perforation in patients with metastatic renal cancer treated with a molecularly targeted drug].

(Case 1) An 82-year-old man started immunotherapy with interferon because of lung metastasis 5 years after he had undergone radical nephrectomy. Three years later, he developed multiple metastases, and was started on sorafenib (400 mg/day) and nonsteroidal anti-inflammatory drug (NSAID) orally. As his cancer-related pain worsened with time, he was administered 30 Gy radiation therapy for bone metastasis of L4. He was then admitted to our hospital for pain control because of ineffective radiation therapy. One day, he suddenly had abdominal pain and vomiting, and was diagnosed as bowel perforation based on computed tomography. He was managed conservatively by nasogastric suction and antibiotic course. (Case 2) A 62-year-old man diagnosed as metastatic renal cell cancer began immunotherapy soon after undergoing radical nephrectomy in Dec., 2006. Although he was started on oral sorafenib (800 mg/day) in July, 2008, metastatic foci enlarged after 18 months. He was then changed to sunitinib (50 mg/day). Sunitinib had immediate and long-lasting effect on the cancer for about 10 months, but he was then admitted to our hospital for pleural effusion. While under treatment for thoracic cavity drainage, he experienced upper abdominal pain and was diagnosis as bowel perforation based on computed tomography. He underwent emergency laparotomy. Molecular target drugs such as sorafenib and sunitinib have serious adverse effects. Bowel perforation is rare, but among those adverse effects. It should be remembered that caution is required for long-term use or combined radiation therapy and NSAIDs with molecular target drug.