Gastrointestinal Stromal Tumors (GISTs) Staging 

Updated: Mar 06, 2018
  • Author: Shamudheen Rafiyath, MD; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
  • Print

TNM Classification, Histologic Grade, Prognostic Stage, and Risk Stratification

The American Joint Committee on Cancer tumor/node/metastasis (TNM) classification for gastrointestinal stromal tumors (GISTs) is provided below, along with anatomic stage/prognostic groups. [1]

Table 1. TNM classification of gastrointestinal stromal tumors (Open Table in a new window)

Primary tumor (T)

TX

Primary tumor cannot be assessed

T0

No evidence of primary tumor

T1

Tumor ≤ 2 cm

T2

Tumor > 2 cm but ≤ 5 cm

T3

Tumor > 5 cm but ≤ 10 cm

T4

Tumor > 10 cm in greatest dimension

Regional lymph nodes (N)

N0

No regional lymph node metastasis

N1

Regional lymph node metastasis

Distant metastasis (M)

M0

No distant metastasis

M1

Distant metastasis

Table 2. Histologic grade (Open Table in a new window)

Histologic grade (G)

GX

Grade cannot be assessed

G1

Low grade; mitotic rate 5/50 per high-power field (HPF) or less

G2

High grade; mitotic rate > 5/50 HPF

 

Table 3. Anatomic stage/prognostic groups for gastric and omental GISTs (Open Table in a new window)

Stage

T

N

M

Mitotic rate

IA

T1 or T2

N0

M0

Low mitotic rate

IB

T3

N0

M0

Low mitotic rate

II

T1

N0

M0

High mitotic rate

T2

N0

M0

High mitotic rate

T4

N0

M0

Low mitotic rate

IIIA

T3

N0

M0

High mitotic rate

IIIB

T4

N0

M0

High mitotic rate

IV

Any T

N1

M0

Any rate

Any T

Any N

M1

Any rate

Table 4. Anatomic stage/prognostic groups for small intestinal, esophageal, colorectal, mesentric, and peritoneal GISTs (Open Table in a new window)

Stage

T

N

M

Mitotic rate

I

T1 or T2

N0

M0

Low mitotic rate

II

T3

N0

M0

Low mitotic rate

IIIA

T1

N0

M0

High mitotic rate

T4

N0

M0

Low mitotic rate

IIIB

T2

N0

M0

High mitotic rate

T3

N0

M0

High mitotic rate

T4

N0

M0

High mitotic rate

IV

Any T

N1

M0

Any rate

Any T

Any N

M1

Any rate

The decision whether to pursue adjuvant treatment depends on an estimation of risk of recurrence, which is typically based on the following factors [2, 3] :

  • Tumor size
  • Mitotic index
  • Location within the GI tract
  • Presence or absence of tumor rupture

Table 5. Modified National Institutes of Health risk stratification criteria for GIST

Table. (Open Table in a new window)

Risk category Tumor size (cm) Mitotic index (per 50 HPFs) Primary tumor site
Very low risk < 2.0 ≤ 5 Any
Low risk 2.1 to 5.0 ≤ 5 Any
Intermediate risk 2.1 to 5.0  > 5 Gastric
< 5.0 6 to 10 Any
5.1 to 10.0 ≤ 5 Gastric
High Risk Any Any Any, with tumor rupture
>10  Any Any
Any >10 Any
> 5 > 5 Any
2.1 to 5.0 > 5 Nongastric
5.1 to 10.0 ≤ 5 Nongastric