Disease-free Interval Is Associated with Oncologic Outcomes in Patients with Recurrent Gastrointestinal Stromal Tumor

Background: Gastrointestinal stromal tumors (GIST) commonly recur following curative-intent resection. Patients with recurrent GIST display heterogeneous outcomes with limited prognostic tools. We investigated factors associated with post-recurrence survival (PRS) and progression-free survival (PFS). Methods: We performed a review of our institutional cancer registry from 2003 to 2018 for patients with GIST. Clinicopathologic and outcome data were collected. The disease-free interval (DFI) was calculated from the end of curative-intent oncologic therapy until recurrence. Outcomes were evaluated using Kaplan–Meier and Cox proportional hazards modeling. Results: Overall, 254 patients underwent resection of primary, non-metastatic GIST, with 81 (32%) recurrences. The median age was 58 years and more than half of the patients with recurrence (n = 44; 54%) received adjuvant imatinib. Recurrence was most common in the liver (n = 34, 42%), peritoneum (n = 31, 38%), or liver plus peritoneum (n = 10, 12%). The median DFI was 14 months (interquartile range 2–26 months); 51 (63%) patients had a DFI ≤24 months and 30 (37%) had a DFI > 24 months. The median post-recurrence follow-up was 46 months. Compared with a DFI ≤24 months, patients with a DFI >24 months had increased 10-year PRS (77% vs. 41%, p < 0.05) and 10-year PFS (73% vs. 19%, p < 0.001). On multivariable analysis controlling for mutational and clinicopathologic features, a DFI >24 months was independently associated with increased PRS (hazard ratio [HR] 0.24, p < 0.01) and PFS (HR 0.18, p < 0.001). Conclusions: The DFI is independently associated with oncologic outcomes in recurrent GIST and may be useful in treatment planning. Recurrence after 24 months may signify indolent disease biology that may benefit from additional treatment, including metastasectomy.