Objective To investigate the clinicopathological characteristics and prognostic factors of gastrointestinal stromal tumor (GIST) with initial surgical resection.

Methods The retro-spective cohort study was conducted. The clinicopathological data of 847 GIST patients who under-went initial surgical resection in Tianjin Medical University Cancer Institute & Hospital from January 2011 to December 2020 were collected. There were 405 males and 442 females, aged (60±10)years. Measurement data with normal distribution were represented as Mean±SD, and comparison between groups was conducted using the t test. Measurement data with skewed distribution were represented as M(range). Count data were described as absolute numbers or percentages, and comparison between groups was conducted using the chi-square test. Comparison of ordinal data was conducted using the nonparameter rank sum test. The Kaplan-Meier method was used to calculate survival rates. Univariate analysis was conducted using the Log-rank test. Multivariate analysis was conducted using the COX regression model.

Results (1) Clinicopatholo-gical characteristics. Of 847 patients, the tumor primary location was stomach in 585 cases, jejunum and ileum in 142 cases, duodenum in 76 cases, colorectum in 10 cases, esophagus in 3 cases, and extra-gastrointestinal in 31 cases. There were 13 cases with liver metastasis and 22 cases with abdominal metastasis. The tumor maximum diameter was (7±5)cm, and the number of nuclear divisions was 4(range, 0-60) cells/50 high-power field or 5 mm². According to risk classification of National Institutes of Health (NIH), 31 cases were of extremely low risk, 238 cases were of low risk, 213 cases were of moderate risk, 365 cases were of high risk. There were 839 of 847 patients positive for CD117, 788 cases positive for Dog-1, 710 cases positive for CD34, respectively. There were 272 cases with Ki-67 < 5%, 214 cases with Ki-67 of 5%- 9%, 198 cases with Ki-67 ≥10%, 163 cases with missing data. R₀ resection was in 814 cases and non-R₀ resection was in 33 cases. (2) Gene testing and postoperative adjuvant therapy of GIST patients. ① Gene testing. Of 847 patients, 424 underwent genetic testing. The proportion of genetic testing was 1.89%(1/53) in 2011, 9.76%(8/82) in 2012, 8.45%(6/71) in 2013, 15.66%(13/83) in 2014, 50.00%(40/80) in 2015, 55.26%(42/76) in 2016, 73.86%(65/88) in 2017, 68.27%(71/104) in 2018, 80.65%(75/93) in 2019, 88.03%(103/117) in 2020, respectively. Of 424 with genetic testing, 338 cases had KIT mutation, 31 cases had PDGFRA mutation, 55 cases were wild type. ② Adjuvant therapy. Of 847 patients, 253 patients underwent postoperative adjuvant therapy. The proportions of postoperative adjuvant therapy were 8.82%(21/238), 41.78%(89/213), 39.18%(143/365) in patients of low risk, moderate risk, high risk. Of 578 patients with moderate to high risk, the proportion of postoperative adjuvant therapy was 15.15%(5/33) in 2011, 14.71%(10/68)in 2012, 22.45%(11/49) in 2013, 29.09%(16/55) in 2014, 41.38%(24/58) in 2015, 46.15%(24/52) in 2016, 32.81%(21/64)in 2017, 60.00%(45/75) in 2018, 60.42%(29/48) in 2019, 61.84%(47/76) in 2020, respectively. Of 253 patients underwent postoperative adjuvant therapy, 247 cases received imatinib had 6 cases received sunitinib. (3) Comparison of clinicopathological characteristics of GIST with non-gastric origin and gastric origin. Of 847 patients, 262 cases had non-gastric origin and 585 cases had gastric origin. There were significant differences in gender, the number of tumor, tumor maximum diameter, Ki⁃67 index, risk classification of NIH, and R₀ resection between the two groups (χ²=8.62, 8.40, 12.97, 6.57, Z=-6.15, χ²=17.19, P < 0.05). (4) Analysis of influencing factors for recurrence-free survival rate in GIST patients. Results of multivariate analysis showed that the year of initial diagnosis, primary site, tumor maximum diameter, mitotic image, risk classification of NIH, R₀ resection, genetic testing and postoperative adjuvant therapy were independent factors influencing recurrence-free survival rate in GIST patients with initial surgical resection (hazard ratio=0.58, 0.61, 2.00, 1.71, 5.81, 2.56, 0.65, 0.38, 95% confidence interval as 0.39-0.85, 0.45-0.83, 1.46-2.74, 1.24-2.35, 3.16-10.69, 1.63-4.02, 0.46-0.94, 0.25-0.56, P < 0.05).

Conclusions GIST with initial surgical resection is common located in stomach, with high positive rate in CD117 and Dog-1. The number of people undergoing genetic testing and targeted therapy for GIST is increasing year by year. There are significant differ-ences in clinicopathological characteristics between GIST with non-gastric origin and gastric origin. The year of initial diagnosis, primary site, tumor maximum diameter, mitotic image, risk classifica-tion of NIH, R₀ resection, genetic testing and postoperative adjuvant therapy are independent factors influencing recurrence-free survival rate in GIST patients with initial surgical resection.