Clinicopathological Features, Clinical Efficacy on 101 Cases of Rectal Gastrointestinal Stromal Tumors, and the Significance of Neoadjuvant Therapy

Objective: To investigate the clinicopathological features, clinical efficacy on 101 cases of rectal gastrointestinal stromal tumors (GISTs), and the significance of Imatinib Mesylate (IM) neoadjuvant therapy. Methods: : The clinicopathological features, treatment methods, peri-operative data, and prognosis of the patients were summarized and analyzed on 101 patients with rectal GISTs, who received treatment in the Gastrointestinal Department of West China Hospital of SichuanUniversity and the Affiliated Hospital of Guizhou Medical University from August 2002 toNovember 2020 in China. Results: : A total of 101 patients, including 64 males and 37 females, were aged from 22 to 79 years (55.4±12.2 years). Among 70 patients with direct surgery, which included 8 very low risk cases, 10 low risk cases, 7 intermediate risk cases, and 45 high risk cases. Cox regression analysis showed that post-operative IM adjuvant treatment improved disease-free survival (DFS) and overall survival (OS) of 52 intermediate and high risk patients. Among the 31 patients who received neoadjuvant therapy, the objective response rate (ORR) was 83.9% (26/31), and the disease control rate (DCR) reached 96.8% (30/31). Diameter subgroup analysis: (1) Among the 36 patients with a diameter ≤ 5 cm, two patients received IM neoadjuvant therapy, while 34 patients received direct surgery. Both univariate and Cox regression analysis did not find that neoadjuvant therapy affects DFS and OS. (2) Among the 65 patients of diameter >5 cm, 29 received IM neoadjuvant therapy and 36 received direct surgery. Patients who underwent neoadjuvant therapy had less blood loss (P=0.022) , shorter post-operative hospital stay (P=0.001), increased anal preservation proportion (93.1% VS72.2% , P=0.031), decreased enterostomy proportion (10.3% VS 33.3%, P=0.037) than those who underwent direct surgery. Cox regression analysis suggested that neoadjuvant therapy and post-operative IM adjuvant therapy improved DFS. Conclusion: Rectal GISTs is relatively rare and is a highly malignant tumor, post-operative oral IM therapy can improve DFS and OS of intermediate and high risk patients. In patients with rectal GISTs with diameter > 5 cm, IM neoadjuvant therapy can improve the anal preservation proportion , preserve the structure and function of the organs, reduce enterostomy proportion, and improve prognosis.