GIST is most commonly found in the stomach and small intestine. A new comprehensive analysis of the U.S. Surveillance, Epidemiology, and End Results (SEER) database shows that, contrary to popular dogma, the prognosis for patients who have GIST of the small intestine is no worse than for those with GIST of the stomach. What does this finding mean for the treatment of the corresponding tumors?
The Swiss research team evaluated data from 3011 adults with gastric GIST, 313 with duodenal GIST, 1288 with jejunum/ileum GIST, 139 with colonic GIST, 172 with rectal GIST, and 173 extraintestinal cases. This results in a total sample of 5096 patients (median age 62 years and half women). The basis for the analysis was the U.S. SEER database from 1998 to 2011. The median observation period was 37 months.
Mortality difference smaller than assumed
It was shown that survival between corresponding tumors of the stomach and small intestine did not differ as much as had been assumed.
- Multivariate analyses that included tumor size, stage, and age found comparable survival limitation in duodenal GIST and jejunal/ileal GIST as in gastric GIST. The hazard ratio for death in general versus gastric cases in duodenal GIST was 0.95, and that for cancer-specific death was 0.99. The corresponding values for tumors of the jejunum/ileum were 0.97 and 0.95.
- The prognosis was also no worse for stromal tumors of the rectum than for corresponding cases in the stomach.
- In contrast, survival was significantly (p<0.001) reduced in colonic and peritoneal GIST: Overall mortality risk increased by 40% in colonic GIST compared with gastric tumors, and cancer-specific mortality risk increased by as much as 89%. With extraintestinal localization, the worse prognosis was reflected in a 42% and 43% increase in risk.
- Other factors that caused poorer cancer-specific survival included tumor size greater than 10 cm, distant and lymph node metastases, and older age.
Reconsidering the approach to small bowel GIST?
The results suggest that the less favorable prognosis of non-gastric GIST is largely due to colon and extra visceral tumors – rather than small bowel and rectal GIST. Thus, one cannot generally assume a worse outcome in intestinal stromal tumors. Risk classifications that attribute a higher risk of tumor-related death to small bowel GIST, for example, should also be reconsidered. This in turn has implications for adjuvant therapy. Is it actually more indicated here than in gastric GIST? And conversely, did adjuvant therapy perhaps affect the results of the present study? The researchers followed up on this and, using data before 2005, when adjuvant therapy with imatinib was not common in GIST, came to the same conclusion: small bowel and rectal GIST condition survival comparable to gastric GIST.
Source: Guller U, et al.: Revisiting a dogma: similar survival of patients with small bowel and gastric GIST. A population-based propensity score SEER analysis. Gastric Cancer 2017; 20(1): 49-60.
InFo ONCOLOGY & HEMATOLOGY 2017; 5(2): 3.
