Molecular basis and management of gastrointestinal stromal tumors

Table 1 Risk stratification of primary GISTs

Tumor feature		Risk of tumor progression
Mitotic index	Size (cm)	Stomach	Small bowel1
< 5/50 HPF	≤ 2	Very low	Very low
	> 2 ≤ 5	Very low	Low
	> 5 ≤ 10	Low	Moderate
	> 10	Moderate	High
≥ 5/50 HPF	≤ 2	Very low	Moderate
	> 2 ≤ 5	Moderate	High
	> 5 ≤ 10	High	High
	> 10	High	High

Modified from Hornick et al[33] Copyrighted permission from Elsevier Inc.

¹GISTs arising from other sites should probably be stratified as small bowel tumors. GISTs: Gastrointestinal stromal tumors; HPF: High power fields.