Accuracy of Pre-operative Imaging in Determining Duodenal Invasion in Gastric Cancer

Authors
Dr Danson Yeo, AZ Sameera Zeehan

Objectives
The role of imaging in pre-operative staging of gastric cancer to evaluate for local extent, nodal involvement and distant metastases is well-established. Computed tomography (CT) scan of the thorax/abdomen/pelvis is generally the preferred first-line imaging modality. Gastric cancer that are located in the antral or pyloric region may involve the duodenum. Pre-operative diagnosis of duodenal invasion is difficult as it is often infiltrative and invades directly via the submucosal or subserosal layer. Accurately defining duodenal involvement is crucial as it impacts surgical procedures including achieving sufficient distal surgical margins. The accuracy of pre-operative imaging is reported from actual clinical cases in determining duodenal invasion in gastric cancer.

Methods
Retrospective review of medical records of patients who underwent subtotal gastrectomy for gastric cancer and had duodenal invasion in a tertiary surgical unit in a single institute between January and May 2024. Pre-operative imaging was compared with post-operative pathologic findings to determine accuracy.

Results
Three patients with locally advanced gastric cancer with duodenal invasion underwent subtotal gastrectomy with D2 lymph node dissection. All three patients had pre-operative oesophagogastroduodenoscopy with biopsy-confirmed gastric adenocarcinoma and CT imaging for staging.

Case 1’s CT reported pylorus thickening and possible D1 involvement. This correlated with intra-operative findings and final histology confirmed duodenal invasion.

Case 2’s CT only reported irregular thickening along gastric antropyloric region. Subsequent magnetic resonance imaging (MRI) reported a gastric pylorus mass but no definite D1 involvement. Intra-operatively, no duodenal involvement was noted. Final histology revealed intestinal type gastric adenocarcinoma with duodenal extension.

Case 3’s CT reported irregular mural thickening but gastric mass was not well-depicted. She underwent neoadjuvant chemotherapy and repeat CT thereafter reported pyloric mass with extension into proximal duodenum. This correlated with intra-operative findings and final histology.

Conclusion
Among the three patients, pre-operative CT imaging did not accurately identify duodenal involvement in gastric cancer in one of them. This patient also had MRI and PET-CT imaging, which did not aid in accurate pre-operative identification of duodenal invasion. Diagnostic laparoscopy is recommended in cases where duodenal invasion is suspected to determine resectability. In selected cases with duodenal involvement, subtotal gastrectomy can still be performed with negative margins without the need for a Whipple’s surgery.