What are the steps for managing gastric cancer per stage, including contouring and radiation therapy details?

Management of Gastric Cancer: A Comprehensive Stage-Based Approach

The management of gastric cancer requires a multidisciplinary approach with treatment strategies tailored to disease stage, incorporating surgery as the cornerstone of curative treatment, along with appropriate perioperative chemotherapy and/or radiation therapy to optimize survival outcomes. 1

Diagnosis and Staging

Initial Diagnosis

• Diagnosis should be made from gastroscopic or surgical biopsy reviewed by an experienced pathologist, with histology reported according to World Health Organization criteria 1
• 90% of gastric cancers are adenocarcinomas, divided into diffuse (undifferentiated) and intestinal (well-differentiated) types 1

Comprehensive Staging

• Physical examination, blood count and differential, liver and renal function tests 1
• Endoscopy and CT scan of thorax, abdomen, and pelvis 1
• Endoscopic ultrasound (EUS) to determine proximal and distal extent of tumor and T stage (less useful for antral tumors) 1
• Laparoscopy with/without peritoneal washings recommended for all potentially resectable cases to exclude metastatic disease 1
• PET scans may upstage patients but can be negative in mucinous and diffuse tumors 1
• Staging should follow the TNM system and AJCC stage grouping 1
• A minimum of 15 examined lymph nodes (optimally at least 25) are recommended for adequate staging 1

Stage-Specific Management

Stage I Disease

• Primary surgical resection with appropriate lymph node dissection 1
• Endoscopic resection may be considered for select early gastric cancers (T1a) with low risk of lymph node metastasis 1
• Follow-up surveillance includes medical examinations, blood tests including tumor markers, CT/US imaging, and endoscopy at regular intervals 1

Stage II-III Disease

• Multidisciplinary treatment planning is mandatory, comprising surgeons, medical and radiation oncologists, gastroenterologists, radiologists, and pathologists 1
• Perioperative chemotherapy approach: Three cycles of pre- and postoperative ECF (epirubicin 50 mg/m², cisplatin 60 mg/m², and continuous IV infusion of 5-FU 200 mg/m²/day) or ECX (substituting capecitabine for 5-FU) significantly improves 5-year survival from 23% to 36.3% 1
• Postoperative chemoradiation approach: Five cycles of postoperative chemotherapy with 5-FU/leucovorin before, during, and after radiotherapy (45 Gy in 25 fractions over 5 weeks) - standard in the USA but less accepted in Europe 1
• Adjuvant chemotherapy approach: In patients with D2 or greater dissection, oral S-1 for 12 months has shown improved 3-year overall survival (81.1% vs. 70.1% with surgery alone) 1

Stage IV Disease (M1)

• Conversion therapy with systemic chemotherapy is recommended with possibility of surgery if favorable response 2
• Consider alternative approaches for specific metastatic patterns:
  • Trans-catheter arterial chemoembolization (TACE) for limited liver lesions 2
  • Neoadjuvant intraperitoneal plus systemic chemotherapy (NIPS) for peritoneal carcinomatosis 2
• Best supportive care should be integrated throughout treatment to prevent and relieve suffering and support quality of life 1

Surgical Approaches

Extent of Resection

• Surgical resection is the only potentially curative treatment for stages I-IV M0 1
• Type of gastrectomy depends on tumor location and extent:
  • Distal gastrectomy for distal tumors with adequate proximal margin
  • Total gastrectomy for proximal tumors or those involving the body with extensive spread 1
  • Proximal gastrectomy for selected proximal tumors 1

Lymph Node Dissection

• The extent of optimal regional lymphadenectomy is debated 1
• Several randomized trials have failed to show superiority of extended (D2-3) over limited (D1) lymphadenectomy 1
• However, a minimum of 14, and optimally at least 25 lymph nodes should be recovered 1
• Japanese trials have shown benefit with D2 dissection when performed by experienced surgeons 1

Minimally Invasive Approaches

• Laparoscopic surgery has shown safety and faster recovery with equivalent nodal harvest in distal gastrectomy 1
• Meta-analysis demonstrated longer duration of surgery and reduced nodal harvest with laparoscopic compared to open surgery 1
• Careful study and audit are recommended as experience develops 1

Radiation Therapy Details

Indications

• Preoperative or postoperative as part of multimodality treatment 1
• Palliative treatment for bleeding or obstruction 1

Dose and Fractionation

• Standard postoperative dose: 45 Gy in 25 fractions over 5 weeks 1
• Consider dose modification based on normal tissue constraints, particularly for the lungs 1

Contouring Guidelines

• Every effort should be made to keep lung volume and doses to a minimum 1
• DVH (dose-volume histogram) parameters as predictors of pulmonary complications are an area of active development 1
• Target volumes should include the tumor bed, anastomosis, and regional lymph nodes at risk 1

Landmark Trials

• MAGIC Trial: Demonstrated benefit of perioperative ECF chemotherapy with improvement in 5-year survival from 23% to 36.3% 1
• Intergroup 0116 Trial: Showed benefit of postoperative chemoradiation with 15% improvement in 5-year overall survival 1
• ACTS-GC Trial: Demonstrated benefit of adjuvant S-1 chemotherapy after D2 dissection with improved 3-year survival (81.1% vs. 70.1%) 1

Palliative Care and Supportive Management

Bleeding Management

• Endoscopic hemostatic interventions for acute bleeding 1
• Interventional radiology angiographic embolization when endoscopy is not helpful 1
• External-beam radiation therapy for both acute and chronic bleeding 1

Obstruction Management

• Endoscopic approaches: balloon dilation, placement of enteral stent 1
• Surgical options: gastrojejunal bypass or gastrectomy in select patients 1
• Establish enteral access for hydration and nutrition if endoscopic lumen restoration is unsuccessful 1
• External-beam radiation therapy and chemotherapy may provide symptomatic relief 1

Follow-up Recommendations

• Regular medical examinations, assessment of performance status, and body weight monitoring 1
• Blood tests including tumor markers 1
• CT and/or ultrasound imaging at regular intervals 1
• Endoscopy at 6 months, then at 2 and 5 years post-surgery 1
• More intensive follow-up for higher stage disease 1

Clinical Pearls and Pitfalls

• The best management for any cancer patient is in a clinical trial; participation is especially encouraged 1
• Multidisciplinary treatment planning is mandatory for optimal outcomes 1
• Poor nutritional status after gastrectomy may reduce tolerance to adjuvant therapy, potentially compromising efficacy 3
• Neoadjuvant approaches may be advantageous by avoiding the problems associated with post-surgical treatment 3
• Despite advances in perioperative therapies, early detection remains crucial for improving outcomes 4, 5
• Consider genetic counseling for patients with family history of gastric cancer, particularly for those with suspected hereditary syndromes 1