Researchers attempted to understand the evolving epidemiology of gastrointestinal stromal tumors in major organ sites.
Throughout the last 20 years, the incidence of gastrointestinal stromal tumors (GISTs) has increased significantly in various patient populations, according to SEER data presented in a JAMA Network Open study.1 Compared with overall GIST incidence, the data regarding mortality rates were only significant in certain populations, such as Black individuals reporting higher mortality than White participants. Future research should explore the external factors potentially impacting GIST, including lifestyle, environment, and low income.
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GISTs are a type of mesenchymal tumor that often appears in the stomach or small intestine of older adults. Most GISTs were originally considered muscle tumors, neurofibromas, or schwannomas. However, they were then considered their own distinct tumor type by 1998, when gain-of-function mutations in KIT as a key oncogenic driver were identified.
“A sharp increase in the incidence of GISTs was observed in 2000 to 2005, mainly due to reclassification of sarcomas as GISTs and increased disease awareness. Until recently, most GISTs with favorable characteristics had been classified as ‘benign’ tumors or tumors ‘with uncertain malignant potential’ and, therefore, were not recorded,” wrote authors of the study.1 “The second and most recent update…classifies all GISTs as malignant; therefore, an increase in incidence after 2020 is expected.”
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As more research is conducted and diagnostic technology is improved, researchers predict an increase of GIST incidence in the future. But according to a 2022 Cancers (Basel) population-based study, GIST is not significantly prominent worldwide and its incidence in the US is rather minimal. “The incidence of GIST is 10–15 cases per million worldwide, with ~5000 cases per year in the United States,” wrote the authors.2
Using representative data from the Surveillance, Epidemiology, and End Results (SEER) program, researchers examined patients over 20 with GISTs diagnosed from January 1, 2000, to December 31, 2019. SEER-22 and SEER-17 data were both included in this study. Researchers also determined organ site trends in incidence rates and annual percent changes estimated by race and ethnicity, as well as sex and age when possible.1
Analyzing GIST incidence and mortality data from the SEER program, 23,001 individuals were included in the SEER-22 dataset while 12,109 were included in the SEER-17 dataset. In the SEER-22 group (mean age, 64 years; 51.3% men; 19.6% Black), GIST incidence significantly increased throughout the 20-year study period. In the SEER-17 group (mean age, 64 years; 51.9% men; 17.8% Black), however, Black participants had a higher mortality rate than those who were White, displaying the only significant race-related finding highlighted by the study authors.
“As expected, there was a sharp increase in incidence rates between 2000 and 2005, mainly related to coding reclassification. However, we observed a continued increase in the incidence of GISTs after 2005,” they continued.1
While the study results made researchers believe other reasons outside of reclassification could have caused the 20-year increase in GISTs, diagnostic tools have become increasingly more useful for identifying patients with GISTs. Diagnosis guidelines have also gone unchanged in the past 20 years. “These recommendations include endoscopic ultrasound and imaging, mainly with computerized tomography as the initial workup. Consideration of magnetic resonance imaging (MRI) is recent,” they wrote.
Finally, circling back to the mortality of patients with GISTs, male sex, older age at diagnosis, advanced stage at diagnosis, tumor size greater than 5 centimeters, poorly and undifferentiated grade, and early year of diagnosis were all associated with increased mortality.
In regard to GIST incidence and mortality, guideline changes and diagnostic shifts in recent history show that this particular disease needs further research to understand a larger scope of the prominence of GISTs worldwide. This study shows that as diagnostic technology increases and improves, so will the incidence of GISTs.
“In this cohort study, the increasing incidence of digestive GISTs among several population groups could not fully be explained by coding reclassification and advances in diagnostic technologies. Future research should explore lifestyle-related or environmental factors underlying the unfavorable trends observed,” concluded the authors.1
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