Abstract: Objective To investigate the clinical characteristics, treatment strategies and curative effect of recurrence and metastasis of primary gastrointestinal stromal tumor (GIST) after complete resection along with adjuvant therapy with imatinib, and to analyze the risk factors of recurrence and metastasis after adjuvant therapy. Methods The demographic data, clinicopathological characteristics and follow-up data of 80 primary GIST patients who received adjuvant therapy with imatinib for at least 1-year duration and had already stopped taking imatinib from January 2005 to December 2017 in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology were analyzed retrospectively. The survival analysis was performed using Kaplan-Meier approach. Univariate analysis was conducted using log-rank test. Multivariate analysis was produced by Cox regression model. Results Of the enrolled 80 patients, recurrence and metastasis were detected in 17 cases after completion of postoperative adjuvant therapy with imatinib, with a median recurrence time of 12 months. All the 17 patients showed no specific clinical manifestations. Liver metastasis, peritoneum metastasis and local recurrence were found in 9, 5 and 3 cases, respectively. In the 17 patients with recurrence and metastasis, 9 patients received imatinib monotherapy. Among the 9 patients, 6 achieved partial responses, while 3 demonstrated stable disease, and secondary drug resistance was found in 7 patients during the follow-up period, with a median progression-free survival of 35 months (95%CI: 15-55 months) and median overall survival of 49 months (95%CI: 30-68 months). A total of 7 patients with recurrence and metastasis were treated with imatinib after operation and achieved satisfying tumor control, and secondary drug resistance was found in 4 patients during the follow-up period, with a median progression-free survival of 31 months (95%CI: 6-56 months) and fell short of median overall survival. The remaining 1 patient gave up treatment. Univariate analysis showed that tumor location (χ2=4.120, P=0.042), preoperative neutrophil-to-lymphocyte ratio (NLR) (χ2=7.513, P=0.006) and preoperative platelet-to-lymphocyte ratio (PLR) (χ2=6.575, P=0.010) were associated with recurrence and metastasis of GIST patients after completion of adjuvant therapy. Multivariate analysis revealed that tumor location (HR=3.787, 95%CI: 1.126-12.732, χ2=4.631, P=0.031) was an independent prognostic factor for those patients. Conclusion GIST patients who are identified recurrence and metastasis after completion of adjuvant imatinib treatment show no specific clinical manifestations after stopping andjuvant therapy with imatinib. Compared with gastric GIST, non-gastric origin GIST has a higher risk of recurrence. Imatinib monotherapy and surgery combined with imatinib therapy are both effective in treating this subgroup of patients.

Key words: Gastrointestinal stromal tumor, Neoplasm recurrence, local, Neoplasm metastasis, Imatinib