Small intestine cancer diagnostic study of choice

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Qurrat-ul-ain Abid, M.D.[2]

Overview

The diagnosis of a small intestine cancer is often made late as the symptoms are nonspecific (abdominal pain, weight loss, nausea and vomiting, occult GI tract bleeding). Early diagnosis requires a high index of suspicion. Histopathological analysis by tissue sample through biopsy of the lesion is the gold standard.

Diagnostic Study of Choice

Gold Standard

• Biopsy is the gold standard test for the diagnosis of small intestine cancer.
• Endoscopy and imaging tests may locate the mass, however, the only way to confirm the diagnosis is to do a biopsy and histopathological analysis.
• There are numerous ways to take biopsy of small intestine:
  • Endoscopic biopsy: Endoscopy may be used to biopsy the lesions of proximal duodenum to the ligament of Treitz or in the terminal ileum. Push enteroscopes may reach the proximal jejunum, but not distal jejunum and ileum.
  • Laproscopic biopsy: It is useful for the diagnosis of malignancy when the laboratory workup is negative and for obtaining an adequate tissue samples of intestinal lesions.
  • Exploratory laparotomy: This may be done if the tumor cannot be reached with an endoscope.It is the most sensitive diagnostic study and is needed to biopsy a tumor in the intestine.

Diagnostic results

• Biopsy samples are used to study histopathlogy of the lesions to confirm the diagnosis.
• Summary of histology of different intestinal cancers is described in the table below:

Histology	Typical appearance
Adenocarcinoma	Polypoid lesions Complete bowel obstruction Heterogenous enhancement
Carcinoid	Single or multiple filling defects Desmoplastic reaction of the mesentery Hypervascularity in the lesions
Lymphoma	Segmental wall thickening with ulceration and necrosis Lymphyadenopathies Dilatation of bowel loops
GIST	Large mass with homogeneous enhancement Necrosis and ulceration Located in ileum
Metastases	Nodules in submucosal layers and in mesentry and surrounding organs

Sequence of Diagnostic Studies

• Patients with symptoms of small bowel cancer should undergo a complete history, physical examination, and screening for fecal occult blood.
• Laboratory work-up should include:
  • Complete blood count (CBC)
  • Measurement of serum electrolytes
  • Carcinoembryonic antigen (CEA)
  • Liver function tests (LFT).

UGIS/SBFT:

• Fluroscopy is the most commonly used tests to examine the small bowel.
• Barium swallow and Barium enema are used to visualize the lesion of intestine, however, they are not sensitive at detecting small intestinal cancer until very advanced stage.
• Upper GI shows features of mucosal pattern distortion, obliteration and narrowing. Delayed images may show hold up of barium at the site of the lesion.

CT and CT enteroclysis (CTE):

• CT and CTE are modern diagnostic tools used primarily for the detection and localization of small intestinal cancers.

MR enteroclysis (MRE):

• MRE is extensively used for the visualization of small intestinal cancer.

Endoscopy and capsule enteroscopy:

• These are extremely useful modalities to visualize the small intestine pathologies.
• Tumor Markers: the role of tumor markers in the diagnosis of cancer is unclear they are mostly used for the follow up surveillance post treatment.
• The majority of small intestine adenocarcinomas are positive for CEA. other markers that can come positive are: urinary 5-hydroxyindoleacetic acid (5-HIAA), serum chromogranin A (CGA) and serum 5-hydroxytryptamine (5-HT, serotonin)

Staging

The American Joint Committee on Cancer (AJCC) has designated staging by TNM classification to define small intestine cancer:

Primary Tumor (T):

TX	Primary tumor cannot be assessed
T0	No evidence of primary tumor
Tis	Carcinoma in situ
T1a	Tumor invades lamina propria
T1b	Tumor invades submucosa
T2	Tumor invades muscularis propria
T3	Tumor invades through the muscularis propria into the subserosa or into the non-peritonealized perimuscular tissue (mesentery or retroperitoneum) with extension ≤2 cm
T4	Tumor perforates the visceral peritoneum or directly invades other organs or structures (includes other loops of small intestine, mesentery, or retroperitoneum >2 cm, and abdominal wall by way of serosa; for duodenum only, invasion of pancreas or bile duct)

Regional Lymph Nodes (N)

Nx	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Metastasis in 1–3 regional lymph nodes
N2	Metastases in ≥4 regional lymph nodes

Distant Metastasis (M)

M0	No distant metastasis
M1	Distant metastasis

AJCC Stage Groupings

Stage	T	N	M
0	Tis	N0	M0
I	T1	N0	M0
II	T2	N0	M0
IIA	T3	N0	M0
IIB	T4	N0	M0
IIIA	Any T	N1	M0
IIIB	Any T	N2	M0
IV	Any T	Any N	M1