Rectal Gastrointestinal Stromal Tumor (GIST) in the Era of Imatinib: Organ Preservation and Improved Oncologic Outcome

Abstract

INTRODUCTION About 5% of GISTs originate in the rectum and historically radical resection was commonly performed. Little is known about the outcome of rectal GIST in the era of imatinib. METHODS Using a prospectively maintained database, we retrospectively analyzed 47 localized, primary rectal GISTs treated at our center from 1982 to 2016, stratified by when imatinib became available in 2000. Overall, disease-specific, and recurrence-free survival (OS, DSS, and RFS) were analyzed by the Kaplan-Meier method. RESULTS Rectal GISTs represented 7.1% of 663 primary GISTs. There were 17 patients in the pre-imatinib era and 30 in the imatinib era. The 2 groups had similar follow-up, age, gender, Miettinen risk, and distance to the anal verge. In the imatinib era, tumors were smaller at diagnosis (median 4.0 vs. 5.0 cm, p=0.029) and 24 of 30 patients received perioperative imatinib. In high-risk patients, organ-preservation and negative margins were more common in the 13 patients treated with neoadjuvant imatinib compared to the 21 treated directly with surgery. High-risk patients who received perioperative imatinib (n=15) had greater (or nearly significantly greater) 5yr OS, DSS, local RFS, and distant RFS than those (n=19) who did not (91, 100, 100, and 71% compared to 47, 65, 74, and 41%, p=0.049, 0.052, 0.077, 0.051, respectively). In the imatinib era, no patient has had a local recurrence or death due to GIST. CONCLUSIONS The use of imatinib is associated with organ-preservation and improved oncologic outcome in rectal GIST.

Frequent rectal gastrointestinal stromal tumor recurrences in the imatinib era: Retrospective analysis of an International Patient Registry

“…Yasui et al found that rectal GISTs frequently recur and most often in a locoregional distribution. Thus, perioperative imatinib has been shown to be effective in reducing locoregional and distant recurrences after tumor resection, even in patients with positive margins . More recently, imatinib has been studied as a neoadjuvant treatment before surgery to reduce tumor burden and aid in operative success .…”

Tailored management of primary gastrointestinal stromal tumors

“…Neoadjuvant IM can facilitate sphincter preservation in certain rectal GISTs. Indeed, patients with GISTs in all of these sites have been commonly selected for neoadjuvant treatment in retrospective series …”

“…Typically, neoadjuvant IM is used to facilitate a sphincter‐preserving operation and avoid an abdominoperineal resection and permanent end colostomy. A full‐thickness resection of the rectal wall is desirable and may sometimes be performed via the transanal approach if distal enough …”

“…Indeed, patients with GISTs in all of these sites have been commonly selected for neoadjuvant treatment in retrospective series. [26][27][28] The current recommendation for those at moderate to high risk of recurrence is 3 years of adjuvant therapy, whether neoadjuvant therapy was used or not. The problem is that, in many patients, risk cannot be fully evaluated because the pretreatment mitotic rate is often not available.…”

“…A full-thickness resection of the rectal wall is desirable and may sometimes be performed via the transanal approach if distal enough. 27 There are also select, mutation-specific surgical considerations. Both SDH-deficient 41 and NF1-associated 42 GISTs can be present as multifocal disease, and their management is not well defined.…”