Gastric carcinoids: Between underestimation and overtreatment

Table 1 Characteristics of GC types

	Type 1	Type 2	Type 3
Percentage (%)	70-85	5-10	15-25
Tumor characteristics	Often small, multiple, polypoid, multicentric	Often small, multiple, polypoid, multicentric	Single, > 1-2 cm, polypoid and often ulcerated
Mean age at diagnosis (yr)	63	50	55
Gender	Females > males	Females = males	Males > females
Associated conditions	Chronic atrophic gastritis type A	ZES/MEN1	Sporadic
Serum gastrin levels	Increased	Increased	Normal
pH of gastric juice	Increased	Low	Normal
Ki-67 (%)	Usually < 2	Usually < 2	Usually > 2
Metastases (%)	2-5	< 10	> 50

Table 2 Clinicopathological characteristics of endocrine tumors of the stomach according to WHO classification[23]

Well-differentiated tumor-carcinoid

Benign behavior: confined to mucosa-submucosa, non-angioinvasive, ≤ 1 cm in size, non-functioning

ECL cell tumor of corpus-fundus associated with hypergastrinemia and chronic atrophic gastritits (CAG) or MEN1 syndrome

Serotonin-producing tumor

Gastrin-producing tumor

Uncertain behavior: confined to mucosa-submucosa, > 1 cm in size, or angioinvasive

ECL cell tumor with CAG or MEN1 syndrome or sporadic

Serotonin-producing tumor

Gastrin-producing tumor

Well-differentiated endocrine carcinoma-malignant carcinoid

Low-grade malignant, deeply invasive (muscularis propria or beyond), or with metastasis

Nonfunctioning

ECL cell carcinoid, usually sporadic, rarely in CAG or MEN1 syndrome

Serotonin-producing tumor

Gastrin-producing tumor

Functioning

ECL cell carcinoid with atypical carcinoid syndrome

Serotonin-producing carcinoid with syndrome

Gastrin-producing carcinoma-malignant gastrinoma

ACTH-producing carcinoma with Cushing syndrome

Poorly differentiate endocrine carcinoma-small cell carcinoma, high grade malignant, usually non-functioning, occasionally with Cushing syndrome

Table 3 Proposed TNM staging system for GC tumors[7]

	Primary tumor
	Depth of invasion			Size
T1	Up to and including muscularis propria			≤ 3 cm
T2	Beyond muscularis propria			≤ 3 cm
T3	Up to and including muscularis propria			> 3 cm
	Beyond muscularis propria			> 3 cm
	Lymph node
N0	No lymph node metastasis
N1	Regional lymph node metastasis
	Distant metastasis
M0	No distant metastasis
M1	Distant metastasis
Disease stage	T	N	M
I	T1	Any N	M0
II	T2	N0	M0
	T3	N0	M0
III	T2	N1	M0
IV	T3	N1	M0
	Any T	Any N	M1