[A case of imatinib-resistant gastrointestinal stromal tumor treated with low-dose sunitinib].

The patient was an 82-year-old man who had undergone resection of a gastrointestinal stromal tumor(GIST)of the small intestine in January 2000, when he was 69 years old. As peritoneal recurrences were diagnosed in June 2002, we performed peritoneal tumorectomy twice, and the perirectal tumor was controlled with imatinib for over 7 years. Resistance to imatinib was diagnosed in March 2011, and treatment was switched to sunitinib. Administration of sunitinib was started at 50mg/day for 28 days followed by treatment withdrawal for 14 days; however, the dose needed to be reduced twice and then discontinued owing to the occurrence of side effects and pemphigoid. During discontinuation of sunitinib, the tumor increased in size and cancer pain appeared; therefore, sunitinib was re-administered at a very low-dose of 12.5mg every alternate day. Low dose sunitinib was effective; the perirectal tumor was reduced and cancer pain disappeared.