Anorectal gastrointestinal stromal tumors: a retrospective multicenter analysis of 15 cases emphasizing their high local recurrence rate and the need for standardized therapeutic approach

This study aims to report our multicenter experience with diagnosis, management, and prognosis of anorectal gastrointestinal stromal tumors (GIST). We retrospectively reviewed cases treated and/or followed up at our institutions in the period 2000-2011. Fifteen patients were identified (eight men and seven women; mean age, 55 years). Presenting symptoms were rectal/perirectal (eight), rectovaginal space (four), or retrovesical/prostatic (three) mass. Primary surgical treatment was local excision (six), deep anterior resection (eight), and palliative diagnostic excision (one). Tumor mean size was 4.8 cm. All but two cases were high risk (Miettinen and Lasota, Semin Diagn Pathol 23:70-83, 2006). R0 resection was achieved in 46 % of cases: one of six local excisions vs. five of seven deep anterior resection (16 vs. 71 %, respectively). All three cases who received total mesorectal excision had R0. Non-R0 status was mainly due to opening of tumor capsule at surgery (Rx). Seven of 14 patients (50 %) developed a parts per thousand yen1 pelvic local recurrences at a mean period of 48.4 months (mean follow-up, 61.6 months). Only two patients developed distant metastasis (adrenal, liver, and peritoneal). Recurrences developed after Rx (three), R1 (two), and unknown R-status (two). Successful mutational analysis in 13 patients revealed KIT mutations in all (10 exon 11, 2 exon 9, and 1 exon 13). Our results confirm the high local recurrence rate of anorectal GISTs (50 %) which correlates with the common practice of suboptimal oncological primary tumor resection (Rx or R1 = 7/13). This uncommon subset of GISTs needs more standardized oncological surgical approach to minimize the propensity for local disease recurrence.