What is the appropriate workup and management for an adult patient with a new diagnosis of gastroesophageal (GE) adenocarcinoma, considering their overall health and past medical history, including previous treatments for gastroesophageal reflux disease (GERD)?

Gastroesophageal Adenocarcinoma: Workup and Management

All newly diagnosed patients with gastroesophageal adenocarcinoma require esophagogastroduodenoscopy with biopsy, CT chest/abdomen/pelvis with contrast, CBC, comprehensive metabolic panel, and universal molecular testing for MSI/MMR status, with HER2, PD-L1, and CLDN18.2 testing if advanced disease is suspected. 1

Initial Diagnostic Workup

Essential Core Studies (All Patients)

• Complete history and physical examination focusing on alarm symptoms (weight loss, dysphagia, vomiting, anemia), duration of GERD symptoms, smoking/alcohol history, and family history of gastric cancers 1

• Esophagogastroduodenoscopy with biopsy to confirm histologic diagnosis (adenocarcinoma vs squamous cell carcinoma), document tumor location, length, circumferential involvement, and degree of obstruction 1, 2

• CT chest/abdomen/pelvis with oral and IV contrast to identify metastatic disease and assess extent of disease 1

• Laboratory studies: CBC and comprehensive chemistry profile including liver and renal function tests 1

• Siewert classification for all esophagogastric junction tumors (Type I: distal esophagus, Type II: true cardia, Type III: subcardial gastric) as this determines surgical approach 1

Universal Molecular Testing (All Patients)

Critical for treatment planning: 1

• MSI status by PCR/NGS or MMR status by IHC - required in all newly diagnosed patients regardless of stage 1

• HER2 testing - mandatory if advanced/metastatic disease documented or suspected, as trastuzumab plus chemotherapy improves survival (13.5 vs 11.1 months) in HER2-positive disease 1

• PD-L1 testing - required if advanced/metastatic disease documented or suspected for checkpoint inhibitor eligibility 1

• CLDN18.2 testing - recommended if advanced/metastatic disease documented or suspected 1

• NGS via validated assay - should be considered for comprehensive molecular profiling 1

Stage-Specific Additional Studies

For potentially resectable disease (no M1 on CT):

• Endoscopic ultrasound (EUS) - preferred method to determine T and N stage, distinguish early-stage (T1a/T1b) from locally advanced disease 1

• Endoscopic resection - essential for accurate staging of suspected T1a or T1b cancers, as it provides definitive histologic assessment of depth of invasion and may be therapeutic 1

• FDG-PET/CT (skull base to mid-thigh) - recommended for locally advanced disease to detect occult metastases; not appropriate for T1 disease 1

For advanced/metastatic disease:

• Biopsy of metastatic sites as clinically indicated for histologic confirmation 1

• Laparoscopy - consider for T3/T4 adenocarcinomas of the esophagogastric junction to rule out peritoneal metastases not visible on CT 1

Supportive Care Assessment (All Patients)

• Nutritional assessment and counseling - mandatory given high risk of malnutrition from dysphagia and tumor burden 1

• H. pylori testing - test and eradicate in all patients with early gastric cancer if positive; recommend testing of close family members 1

• Smoking cessation - advice, counseling, and pharmacotherapy as indicated 1

• Performance status documentation (ECOG or Karnofsky) - determines eligibility for systemic therapy versus best supportive care 2

Management by Stage

Early-Stage Disease (T1a)

Endoscopic resection is first-line treatment for T1a tumors 1

• Endoscopic resection provides both accurate staging and definitive treatment for T1a disease 1

• Endoscopic ablation of residual Barrett's esophagus must follow endoscopic resection of T1a tumors to prevent metachronous lesions 1

• Endoscopic follow-up required after treatment 1

T1b Disease

Offer oesophagectomy to patients with T1b disease who are fit for surgery and at high risk of progression (incomplete endoscopic resection, lymphovascular invasion, or deep submucosal invasion >500 μm) 1

• For patients unfit for surgery with high-risk T1b disease, consider radiotherapy alone or combined with chemotherapy 1

• Endoscopic follow-up required after radiotherapy 1

Locoregional Disease (T2 or Higher, M0)

For medically fit patients with T2 or higher tumors, perioperative chemotherapy is category 1 recommendation 1

• Surgery with adequate lymph node resection (two-field lymphadenectomy) is standard for resectable disease 1

• Transthoracic esophagectomy with gastric tube anastomosis in left neck recommended for intrathoracic tumors 1

• Preoperative radiation alone does not improve survival and is not recommended 1

• For suboptimal surgical resection (positive margins), postoperative chemoradiation improves survival 3

Advanced/Metastatic Disease (M1)

First-line systemic therapy based on molecular profile: 1

• HER2-positive disease: Trastuzumab plus chemotherapy (fluoropyrimidine and platinum) - improves median OS from 11.1 to 13.5 months 1

• PD-L1 positive disease: Checkpoint inhibitor plus chemotherapy 4

• MSI-high tumors: Immunotherapy demonstrates promising results 4

• HER2-negative, PD-L1 negative: Combination chemotherapy (ECF regimen: epirubicin, cisplatin, 5-fluorouracil or modifications) 1, 5

Palliative interventions for symptomatic disease:

• Expandable metal stents for dysphagia 3

• Radiation therapy for bleeding or obstruction 3

• Nutritional support via jejunostomy or parenteral nutrition for obstruction 5

Critical Pitfalls to Avoid

• Do not withhold endoscopy in patients with longstanding GERD/dysphagia - benign stricture cannot be assumed without biopsy 1

• Do not delay antisecretory therapy indefinitely, but ideally withhold until after diagnostic endoscopy to avoid masking malignancy 1

• Do not assume PET-avid lesions are metastatic - histologic confirmation of occult metastases is required as false-positives occur 1

• Do not proceed with surgery alone for T2 or higher disease - perioperative chemotherapy improves outcomes 1

• Do not treat high-grade dysplasia without urgent repeat endoscopy and biopsy - significant proportion already have or will develop intramucosal cancer 1

Multidisciplinary Approach

All patients require evaluation by multidisciplinary team including gastroenterology, medical oncology, surgical oncology, radiation oncology, nutrition, and pathology before initiating treatment, particularly for locoregionally confined tumors 1, 5