Frozen tumor tissue and corresponding blod samples were available from eight patients dia-gnosed with and operated for midgut carcinoid tumors during a 13-year period (August 1983 till February 1996) at the University hospital Uppsala, Sweden. Patients were identified through the medical archives and pathological reports. Access to the pathological and clinical data was approved by the institutional board and the regional research ethics committé. Six of the primary lesions originated in the ileum, one in the ileo-cecal valve and one in the ascending colon. Tissue from two primary tumors, four mesenteric metastases and two liver metastases were investi-gated. All eight tumors had metastasized to the liver and/or the small intestine mesenterium and/ or other sites at the time of surgery. In all patients the carcinoid tumors occurred sporadically as diagnosed by the lack of both personal and family history of the same tumor. The patients were four females and four males with an age range of 43 to 73 years. Clinical and pathological characteristics are displayed in Table 3.

Tumor

number

Localizationof primary tumor

Sample origin

Age at surgery (years)

Localization of

metastases

Follow-up

(years)

2283

Ileum

Lymph node

metastasis

50

Mesenteric lymph nodes,

Liver

AWD (10)

2762

Ileum

Primary tumor

73

Mesenteric lymph nodes,

Liver

AWD (9)

4017

Ileo-cecal

valve

Liver metastasis

71

Mesenteric lymph nodes,

liver

AWD (7)

5184

Ileum

Primary tumor

46

Mesenteric lymph nodes,

liver

AWD (5)

5216

Ileum

Liver metastasis

72

Mesenteric lymph nodes,

liver

AWD (5)

5692

Right Colon

Lymph node

metastasis

70

Mesenteric lymph nodes,

liver

AWD (4.5)

5718

Ileum

Lymph node

metastasis

55

Mesenteric lymph nodes,

liver, breast

AWD (4)

5807

Ileum

Lymph node

metastasis

43

Mesenteric lymph nodes,

liver, bone

AWD (4)

Table 3. Clinical characteristics of cases with malignant midgut carcinoids subjected to genome- wide LOH screening (AWD=alive with disease)