Retrospective analysis of prognostic factors affecting the recurrence and disease-free survival following surgical management of gastrointestinal stromal tumors

Objective: The aim of this study was to evaluate the prognostic factors effecting recurrence risk and disease-free survival of the patients who were diagnosed as gastrointestinal stromal tumor after complete resection of the tumor with or without adjuvant therapy. Material and Methods: Between the years 2005 and 2013, data of 71 patients including clinical and demographic features, tumor localizations, pathologic examinations, survival and recurrence rates were enrolled into this retrospective study. Results: Male/female ratio was 1.71, and mean age was 60.27 +/- 14.65 years. Forty-two (59.2%) patients had tumor in stomach, 16 (22.5%) in small bowel, whereas 12 (16.9%) had extra-gastrointestinal system and one patient (%1.4) had rectal localization. Modified NIH risk stratification scheme categorized 9 (12.68%) patients in very low-, 12 (16.90%) in low-, 21 (29.58%) patients in moderate-and 29 (40.85%) patients in high-risk group. Twenty-four (33.8%) patients had a metastatic disease at follow-up while 13 (18.3%) patients were metastatic at admission. RO resection was successfully performed in 51 (71.8%) patients, while R1 resection in 9 (12.7%) and R2 resection in 11 (15.5%) were achieved. Mean follow-up time was 47.12 +/- 33.52 months (range, 1-171 months). Nineteen (26.8%) patients demonstrated recurrence with a mean time of 22.16 +/- 15.89 months (range, 3-57 months). During follow-up 17 (23.9%) patients were deceased. In univariate analysis, high-risk group, small bowel and extra-gastrointestinal system localization, R1-2 resection, necrosis, positive resection margin and invasion of surrounding tissues, metastatic disease and adjuvant therapy were statistically significant in terms of recurrence. Multivariate analysis presented small bowel and extra-gastrointestinal system localization, R2 resection, mitoses count, invasion and adjuvant therapy as independent prognostic risk factors affecting disease-free survival rates.The 1,3 and 5 years of disease-free survival rates of the patients were 89.6%, 75.4%, 64.3%, respectively. Conclusion: As mentioned in the literature, the mainstay of curative therapy of gastrointestinal stromal tumor is surgery. In our study, not only small bowel, extra-gastrointestinal system localization and invasion of surrounding tissues by tumor, but also R2 resection that complicate the local control of the disease were represented as independent adverse prognostic factors for disease-free survival. Unfavourable clinical outcomes of adjuvant therapy over the disease-free survival was linked to higher tumor stage with metastatic disease and emphasized that prospective trials with more cases should be practiced.