Second primary malignances (SPMs) in patients with gastrointestinal stromal tumors (GIST): The potential influence of imatinib treatment.

10552 Background: GISTs are relatively uncommon and predominantly sporadic tumors of the gastrointestinal tract. The high incidence of SPMs observed in patients (p) with GIST (13-20 %), has suggested a possible cause-and-effect relationship between treatment with imatinib and SPMs. Whether this concomitant occurrence is a causal association or a coincidence is not yet resolved. Methods: We have retrospectively analyzed the incidence of synchronous and metachronous SPMs, in all p diagnosed with GIST and treated at a single institution between 1997 and 2012. Results: A total of 95p were diagnosed with GIST, 18 (19%) of whom developed SPMs. For these 18p, the median age at GIST diagnosis was 61.7 years (range, 27-75). The GIST was located in the stomach in 10p (52.6%) and in the small bowel in 8 (47.4%). The SPMs were more frequent in the colon (4p), breast (4), kidney (3), esophagus (2), lymphoproliferative disease (2), bladder (2), adrenal gland (1), prostate (1), pancreas (1), vocal cord (1) and oligodend...