Metastatic Lesions of the Stomach: Primary Sites
The most common primary sites for metastatic lesions to the stomach are breast cancer (27.9%), lung cancer (23.8%), and esophageal cancer (19.1%), followed by renal cell carcinoma (7.6%) and malignant melanoma (7.0%). 1
Primary Tumor Origins
The spectrum of primary malignancies that metastasize to the stomach has been well-characterized through large autopsy and endoscopic series:
Most Common Primary Sites (in descending order):
- Breast cancer: 27.9% of gastric metastases 1
- Lung cancer: 23.8% 1
- Esophageal cancer: 19.1% 1
- Renal cell carcinoma (RCC): 7.6% 1
- Malignant melanoma: 7.0% 1, though notably melanoma has the highest propensity to metastasize to the stomach (29.6% of melanoma cases with metastases) 2
Additional primary sites include ovarian cancer, cervical cancer, sigmoid colon, testicular cancer, and skin malignancies 1, 3.
Clinical Presentation Patterns
Timing of Metastatic Spread:
The interval between primary tumor treatment and gastric metastasis detection varies significantly by primary site:
- Breast cancer and RCC: Median interval of 50-78 months and 75.6 months respectively, indicating metastatic spread may occur many years after initial cancer treatment 1
- Ovarian cancer: Median interval of 30 months 1
- General range: 0 to 56 months across all primary sites 3
Critical pitfall: In rare cases (documented with lung and breast cancer), gastric metastases may be discovered before the primary tumor is identified 2. This underscores the importance of comprehensive workup when atypical gastric lesions are encountered.
Endoscopic Appearance:
Gastric metastases most commonly present as:
- Submucosal tumors (51-66.7% of cases) 2, 1
- Solitary lesions (65%) more common than multiple lesions (35%) 2
- Location: Preferentially in the middle or upper third of the stomach and gastric body 2, 4
- May mimic primary gastric cancer endoscopically (39% of cases) 2
Diagnostic Approach
Endoscopic biopsy yields diagnosis in over 90% of cases 2, making it the primary diagnostic modality when gastric metastases are suspected.
When to Suspect Gastric Metastases:
- History of breast cancer, lung cancer, RCC, or melanoma—even if treated years previously
- Submucosal gastric lesions on imaging or endoscopy
- Upper gastrointestinal bleeding in patients with known malignancy 3, 4
- Multiple gastric lesions in a patient with known cancer
Prognostic Implications
Gastric metastases indicate advanced disease with poor prognosis: median survival of 4.75-6 months from diagnosis of gastric metastasis 3, 4. Overall 1-year survival is only 20%, with essentially no 2-year survivors 3.
Exceptions with Better Prognosis:
- Breast cancer and RCC metastases may have better outcomes due to availability of effective systemic therapies 5
- Solitary metachronous lesions in highly selected patients may benefit from surgical resection, particularly for hemorrhage control 1
Treatment Strategy
Systemic chemotherapy according to the primary tumor is the preferred therapeutic approach 5. Surgical resection is generally reserved for:
- Control of hemorrhaging 1
- Solitary metachronous metastasis in exceptional cases 1
- Symptomatic relief when systemic therapy is ineffective 4
The rarity of gastric metastases (5.4% of autopsy cases with solid malignancies) 2 means treatment is primarily palliative, focused on symptom management rather than cure.