Z. E. Stiles1, T. M. Rist2, P. V. Dickson1, M. G. Martin2,3, B. G. Somer2,3, E. S. Glazer1, M. D. Fleming1, D. Shibata1, J. L. Deneve1 1University Of Tennessee Health Science Center (UTHSC),Department Of Surgery,Memphis, TN, USA 2University Of Tennessee Health Science Center (UTHSC),College Of Medicine,Memphis, TN, USA 3West Cancer Center,Memphis, TN, USA
Introduction: Potentially curative treatment for gastrointestinal stromal tumors involves resection with adjuvant tyrosine kinase inhibitor (TKI) therapy utilized based on risk of recurrence. An association between obesity and GIST has been previously described with the incidental finding of GIST at the time of gastric resection for bariatric procedures. However, the impact of obesity on long-term GIST outcome is unknown. We examined the relationship of obesity and oncologic outcome in a cohort of patients with resected GIST.
Methods: We performed a retrospective review of patients with resected GIST. Clinically relevant data was obtained from medical records. The impact of obesity, defined as a BMI ≥ 30, on oncologic outcomes was evaluated.
Results: Of 78 patients with GIST, 61 were evaluable and underwent resection for primary or recurrent disease with a median follow up of 22 months (1-129 mo). Fifty-six patients (91%) presented with localized disease involving the stomach (74%), small intestine (18%), or colon/rectum (5%). Nine patients (15%) received pre-operative TKI. Median tumor size was 6 cm (1.4-35 cm) and 11 patients (18%) underwent multivisceral resection with negative margins obtained in 57 (92%). Twenty-seven patients (44%) had a mitotic rate >5/50 HPF. Thirty-five patients (57%) received adjuvant TKI therapy. Ten patients (16%) recurred after initial resection with a median time to recurrence of 26 months. Mean BMI for the cohort was 28.9 ± 6.5. Twenty-four patients (39%) were obese, defined as a BMI ≥ 30. Patients in the non-obese cohort were more likely to undergo multivisceral resection (27.0% vs 4.2%, p=0.023), have multifocal disease (24.3% vs 4.2%, p=0.038), and have larger primary tumor diameter (10.7 ± 8.6 cm vs 6.2 ± 4.2 cm, p=0.02). A significantly higher proportion of the non-obese patients experienced recurrence of their disease than the obese group (28.1% vs 4.3%, p=0.024). There was no difference in overall survival between the obesity and non-obesity group.
Conclusion: Among patients undergoing resection for GIST, obese patients had smaller primary tumor diameters, a decreased incidence of multifocal disease, underwent fewer multivisceral resections, and had a lower incidence of disease recurrence. GISTs may represent another example of the “obesity paradox” in which obesity may provide a protective effect on certain cancers. Further large scale studies are warranted to verify the impact of obesity on GIST patient outcomes and to elucidate any underlying clinicopathologic and/or biologic factors.