Preoperative Chemotherapy and Survival for Large Anorectal Gastrointestinal Stromal Tumors: A National Analysis of 333 Cases.

PURPOSE: Anorectal gastrointestinal stromal tumors (GISTs) are exceedingly rare, and management remains controversial in regard to local resection (LR) and preoperative chemotherapy.

METHODS: The National Cancer Data Base was queried from 1998 to 2012 for cases of GIST resection in the rectum or anus. Patient demographics, type of surgery (LR vs. radical excision [RE]), short-term outcomes, and overall survival (OS) were analyzed. Preoperative chemotherapy was recorded following the US FDA approval of imatinib in 2002.

RESULTS: Overall, 333 patients with resection of anorectal GISTs were included. Mean age at presentation was 62.3 years (range 22-90), and median tumor size was 4.0 cm (interquartile range 2.2-7.0). Five-year OS for all patients was 77.6%. In a multivariable survival analysis, only age and tumor size >5 cm (hazard ratio 2.48, 95% confidence interval 1.50-4.01; p = 0.004) were associated with increased mortality. One hundred and sixty-three (49.0%) patients underwent LR, compared with 158 (47.4%) who underwent RE. For tumors smaller than 5 cm, no difference in 5-year survival by surgical approach was observed (LR 82.3% vs. RE 82.6%; p = 0.71). Fifty-nine patients (17.7%) received preoperative chemotherapy; for patients undergoing RE with tumors >5 cm, there was decreased mortality in the group who received preoperative chemotherapy (5-year OS with chemotherapy 79.2% vs. no chemotherapy 51.2%; p = 0.03).

CONCLUSIONS: Size is the most important determinant in survival following resection. Local excision is common, with resection split between LR and RE. For smaller tumors, LR may be adequate therapy. Preoperative chemotherapy may result in improved survival for large tumors treated with radical resection, but the data are imperfect.