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ADENO CARCINOMA OF SMALL BOWEL

Small Bowel Adenocarcinoma

  • Malignancy in small bowel is about 50 times less common than in the colorectum.
    • Low bacterial load
    • Faster transit time

Duodenal Adenocarcinoma

Most Common Site

  • Duodenum: The most common site for adenocarcinoma.
    • Interaction of pancreatic, biliary, and gastric secretions.
    • Free radical injury (ROS) is produced during bile acid receptor activation.
    • Large variations in acid content lead to less repair of cell damage compared to the jejunum and ileum.

Risk Factors

  • Crohn's disease: Increases cancer risk by 60-fold.
  • Polyps:
    • All patients with FAP (Familial Adenomatous Polyposis) will develop duodenal polyps.
    • FAP patients with duodenal polyps have a 5% to 10% risk of developing duodenal cancer by age 60.
  • Celiac Sprue is also a risk factor.

Spigelman Scoring System - Risk of Duodenal Malignancy:

  • Stage 2: Risk = 2.3%
  • Stage 3: Risk = 2.4%
  • Stage 4: Risk = 36%

Spigelman Staging System for Duodenal Adenomas

Criteria 1 Point 2 Points 3 Points
Polyp Number 1–4 5–20 >20
Polyp Size 1–4 mm 5–10 mm >10 mm
Polyp Histology Tubular Tubulovillous Villous
Degree of Dysplasia Low Moderate* High
- Note: Moderate dysplasia is now combined with low-grade dysplasia.

Staging System

  • Stage 0: 0 points
  • Stage I: 1–4 points
  • Stage II: 5–6 points
  • Stage III: 7–8 points
  • Stage IV: 9–12 points
  • Most common site in the small bowel.
  • Majority located in the mid and distal duodenum.
    • 15% of cases seen in the duodenal bulb and postpyloric channel.

Diagnosis

  • UGI Endoscopy: Investigation of choice.
  • CEA & CA 19.9: Elevated in 1/3 of patients.

Surveillance Interval for Upper GI Endoscopy Based on Spigelman Classification

Spigelman Classification Surveillance Interval (Years)
Stage 0/I Every 5 years
Stage II Every 3 years
Stage III Every 1–2 years
Stage IV Consider surgery
- Stage IV polyposis: Resection is advised, and further screening is not recommended.

Treatment

  • Surgical resection: Treatment of choice.
    • D1, D2, D3: Pancreatoduodenectomy.
    • D4: Resection.
    • Adequate lymphadenectomy: Minimum 6 nodes. ? ? ? [ sabiston = 10 & NCCN = 8]
  • Adjuvant chemotherapy: Shown to improve survival (as per ESPAC3 trial).
    • Common regimens: FOLFOX / FOLFIRI.
  • 5-year survival rate: 45-71%.

Prognosis

  • Prognosis after resection depends on:
    1. Extent of nodal involvement.
    2. Perineural/perivascular invasion.
    3. Tumor differentiation.
    4. Margin status after resection.
  • Tumor site or depth of invasion (T stage) are not independently associated with survival.

Jejunal & Ileal Adenocarcinoma

  • Asymptomatic in early stages leading to delayed diagnosis and poor prognosis.

Diagnosis

  • CT or MRI are used for diagnosis.

Treatment

  • Curative resection is possible in 45% to 70% of cases.
  • Adjuvant therapy provides a survival advantage.

Small Bowel Adenocarcinoma MCQs

  1. All are true regarding etiopathogenesis of small bowel adenocarcinoma except:
    • a. Low bacterial load
    • b. Transit time is slower (Correct Answer)
    • c. The interaction of pancreatic, biliary, and gastric secretions causes a higher incidence of adenocarcinoma of the duodenum
    • d. The large variations in acid content in the duodenum make it less able to repair cell damage, as compared with the jejunum and ileum
  2. In Crohn's disease of the small bowel, risk of adenocarcinoma is increased by:
    • a. 30 fold
    • b. 50 fold
    • c. 60 fold (Correct Answer)
    • d. 80 fold
  3. All are true regarding risk factors for adenocarcinoma of the small bowel except:
    • a. All patients with FAP will develop duodenal polyps, and polyps carry a 100-to 330-fold higher risk
    • b. FAP patients with duodenal polyps have 40-50% risk of duodenal cancer by 60 yrs (Correct Answer: False, the risk is 5-10%)
    • c. Most duodenal polyps are broad-based and not as amenable to endoscopic resection
    • d. Celiac sprue is a risk factor
  4. Most common site of small bowel adenocarcinoma is:
    • a. Duodenum (Correct Answer)
    • b. Jejunum
    • c. Ileum
    • d. All are equal
  5. According to the Spigelman scoring system, the risk of duodenal malignancy in patients with stage 3 polyposis is:
    • a. 2.3%
    • b. 2.4% (Correct Answer)
    • c. 23%
    • d. 24%
  6. All are true statements regarding duodenal adenocarcinoma except:
    • a. Most duodenal lesions are in the mid and distal duodenum
    • b. Only 15% are in the duodenal bulb and postpyloric channel
    • c. UGI endoscopy is the investigation of choice
    • d. CEA & Ca 19-9 are increased in >50% of patients (Correct Answer: False, they are elevated in only 1/3 of patients)
  7. Recommended screening endoscopy in Spigelman stage 2 polyps is:
    • a. Every 6 months
    • b. Every year
    • c. Every 2-3 years (Correct Answer)
    • d. Every 5 years
  8. Prognosis after resection in duodenal adenocarcinoma depends on all except:
    • a. Extent of nodal involvement
    • b. Tumor site (Correct Answer: Tumor site does not independently affect survival)
    • c. Tumor differentiation
    • d. Margin status after resection
  9. Adequate number of lymph nodes needed for duodenal adenocarcinoma resection is:
    • a. 6 (Correct Answer)
    • b. 8
    • c. 10
    • d. 5
  10. Adequate margin required in resection of small bowel adenocarcinoma is:
  11. a. 10 cm
  12. b. 5 cm (Correct Answer) ? ?
  13. c. 8 cm
  14. d. 15 cm