Occurrence of other tumors in patients with GIST

Evaluate the presence of other tumors in cohort of patients with GIST treated at a cancer treatment referral center - INCA.

We reviewed the medical records of patients diagnosed with GIST who were treated at INCA between 1998 and 2008. Immunohistological diagnosis was confirmed by a pathologist specialized in sarcomas. Patients presenting second non-GIST tumors were identified. Age, sex, tumor location, risk groups (according to the National Institutes of Health criteria), characteristics of non-GIST tumors and treatment results were analyzed.

Among the 101 patients diagnosed with GIST who were evaluated during the study period, 14 (13.8%) had other non-GIST tumors, 9 females (64.3%), with a median age of 68 years (10-79 years). The stomach was the location of GISTs in 8 cases (57.1%), followed by the small bowel in 4 cases (28.5%), colon and mesentery with 1 case (7.1%) each. The mean size of lesions was 4.79 cm (0.3-15 cm), with malignant potential low/very low in 7 cases (50%), intermediate in 5 cases (35.7%) and high in 2 cases (14.3%). The diagnosis of GIST was incidental in 6 cases and in one case the non-GIST tumor was incidental. The non-GIST tumors were most frequent in the stomach (adenocarcinoma), in 4 cases (28.5%) and colon/rectum (adenocarcinoma) in 4 other cases. The other sites involved were breast (ductal carcinoma), kidney (clear cell carcinoma), prostate (adenocarcinoma), endometrium (adenocarcinoma), ovary (adenocarcinoma) and adrenal (neuroblastoma), with one case each. The tumors were synchronous in 7 cases (50%). With a median follow-up after GIST resection of 41 months (2-87 months), 9 patients were alive without evidence of disease, 2 died due to GIST, 2 died due to non-GIST tumors and the remaining patient died due to postoperative complications.

We discovered a 13.8% incidence of non-GIST tumors in a series of 101 GIST cases under our care. This association should always be considered in the management of patients with GIST.