What is the management plan for a patient with gastric adenocarcinoma, severe abdominal pain, and imaging findings of a cystic mass, probable early abscess formation, and metastasis?

Management of Gastric Adenocarcinoma with Abscess Formation and Metastatic Disease

This patient requires immediate surgical consultation for urgent intervention to address the probable early abscess formation, combined with broad-spectrum antibiotics and aggressive supportive care, followed by palliative systemic therapy once the acute infectious complication is controlled. 1

Immediate Management Priorities

Acute Abscess and Infection Control

• Initiate broad-spectrum intravenous antibiotics immediately to cover gram-negative and anaerobic organisms, as the CT findings of a thick-walled peripherally enhancing hypodense mass abutting the gastric body strongly suggest early abscess formation 1

• Obtain surgical consultation urgently for potential drainage of the abscess, as persistence of severe pain (10/10) with guarding indicates an acute surgical abdomen that may require intervention 1

• Consider percutaneous drainage if the abscess is accessible and the patient is too unstable for surgery, though surgical drainage may be preferred given the proximity to the gastric wall 1

• Monitor for sepsis with serial vital signs, complete blood counts, and lactate levels, as infected cystic masses in gastric cancer can rapidly progress to systemic infection 1

Pain Management

• Administer intravenous opioids for the 10/10 pain, titrating to effect with continuous monitoring 1

• Avoid oral medications given the likely gastric outlet obstruction indicated by the distended, fluid-filled small intestines with wall thickening 1

• Consider external beam radiation therapy once the acute infection is controlled, as EBRT can effectively manage tumor-related pain in gastric cancer 1

Nutritional Support and Decompression

• Place a nasogastric tube for gastric decompression given the findings of distended, fluid-filled small intestines suggesting obstruction 1

• Establish intravenous hydration immediately, as oral intake is contraindicated with this degree of obstruction 1

• Plan for jejunal feeding tube placement once the acute infection is controlled, as the patient will require nutritional support and cannot tolerate oral intake with gastric body involvement 1

Staging and Molecular Profiling

Essential Testing

• Obtain HER2 testing on the biopsy specimen if not already done, as trastuzumab plus chemotherapy is category 1 first-line therapy for HER2-positive metastatic gastric adenocarcinoma 1

• Test for PD-L1 expression by combined positive score (CPS), as nivolumab combined with chemotherapy is recommended first-line for tumors with CPS ≥5 (category 1) or CPS <5 (category 2B) 1

• Perform MSI/MMR testing, as MSI-H/dMMR tumors respond to pembrolizumab or dostarlimab-gxly in second-line or subsequent therapy 1

• Consider next-generation sequencing (NGS) via validated assay to identify NTRK gene fusions (treatable with entrectinib or larotrectinib) and other actionable mutations 1

Systemic Therapy Planning

Performance Status Assessment

• Assess ECOG performance status once the acute infection is controlled, as systemic therapy decisions depend on whether the patient has ECOG PS ≤2 (eligible for chemotherapy) versus ≥3 (best supportive care only) 1

• Recognize that the current acute presentation with 10/10 pain and probable abscess temporarily precludes systemic therapy until stabilized 1

First-Line Therapy Options (Once Stabilized)

For HER2-positive disease:

• Trastuzumab plus fluoropyrimidine and platinum-based chemotherapy is the category 1 recommendation for first-line therapy 1

For PD-L1 CPS ≥5:

• Nivolumab plus chemotherapy (fluoropyrimidine and platinum) is category 1 first-line therapy 1

For PD-L1 CPS <5 or HER2-negative:

• Fluoropyrimidine plus platinum-based doublet (such as FOLFOX or CAPOX) is standard first-line therapy 1
• ECF/ECX regimen (epirubicin, cisplatin/oxaliplatin, 5-FU/capecitabine) is an alternative based on perioperative trial data, though this patient is not a surgical candidate 1

Palliative Interventions

Obstruction Management

• Endoscopic stent placement should be considered once the infection is controlled if the gastric outlet obstruction persists, though the presence of abscess formation may complicate this approach 1

• Venting gastrostomy tube may be necessary if endoscopic stenting is not feasible due to tumor location or abscess, to provide gastric decompression 1

• Surgical gastrojejunostomy is an alternative if the patient becomes stable enough for surgery and endoscopic approaches fail 1

Ascites Management

• Drain ascites if it develops to reduce risk of infectious complications and improve comfort, though current imaging shows only minimal intra-abdominal fluid 1

• Do not routinely use HIPEC for peritoneal metastasis, as the Phoenix-GC study showed no significant OS benefit in the overall population (17.7 vs 15.2 months, P=0.080) 1

Critical Pitfalls to Avoid

• Do not delay antibiotic therapy while awaiting surgical consultation, as the thick-walled peripherally enhancing hypodense mass with surrounding fat stranding indicates active infection requiring immediate treatment 1

• Do not attempt endoscopic stent placement during the acute infectious phase, as this could worsen the abscess or cause perforation 1

• Do not start systemic chemotherapy until the abscess is drained and infection controlled, as chemotherapy will worsen immunosuppression and infection risk 1

• Avoid surgical resection of the primary tumor in the setting of widespread metastatic disease (omental, lymph node, and subcutaneous nodules), as this provides no survival benefit and carries high morbidity 1

• Monitor for severe pain after any stent placement, as this requires immediate endoscopic removal of the stent 1

Prognosis and Goals of Care Discussion

• Median survival for stage IV gastric adenocarcinoma is approximately 9-10 months with systemic therapy, though this varies based on molecular subtype and treatment response 1, 2

• Initiate palliative care consultation early to address symptom management, goals of care, and quality of life, as best supportive care is an integral part of treatment for metastatic disease 1

• Consider clinical trial enrollment once stabilized, as the NCCN panel strongly encourages participation in well-designed trials investigating novel therapeutic strategies 1