Neoadjuvant Therapy in Treating Stomach (Gastric) Cancer

Explore how neoadjuvant therapy helps treat stomach (gastric) cancer. GetWellGo guides international patients to advanced care and expert cancer treatment options.

Neoadjuvant Therapy in Treating Stomach (Gastric) Cancer

  • Category

    Cancer

  • Published By

    GetWellGo Team

  • Updated on

    19-Jun-2025

Neoadjuvant therapy for gastric cancer

Neoadjuvant therapy is treatments administered prior to the main treatment (often surgery) to reduce the size of the tumor, enhance the success of surgery, and decrease recurrence risk. In stomach cancer, this is typically chemotherapy, with or without radiation.

Objectives of Neoadjuvant Therapy in Stomach Cancer

  • Tumor downsizing – renders initially unresectable or borderline tumors resectable.
  • Improve margins of surgery – increases likelihood of radical (R0) resection.
  • Treat micrometastases early – targets possible spread prior to surgery.
  • Measure treatment response – gives prognostic information.

Stomach cancer treatment before surgery

When stomach cancer is locally advanced but possibly resectable, treatment prior to surgery is usually advised to enhance outcomes. Such treatment prior to surgery is termed neoadjuvant therapy.

Aims of Pre-Surgical Treatment:

  • Reduce the size of the tumor to make surgery simpler and more effective.
  • Destroy microscopic cancer cells that might have spread.
  • Enhance the likelihood of a complete removal (R0 resection).
  • Enhance long-term survival and decrease recurrence.

Methods of Pre-Surgery Treatment:

Neoadjuvant Chemotherapy (most common)

  • Administered prior to surgery over a few weeks.
  • Aids in shrinking tumor size and lymph node burden.

Regimens used:

  • FLOT (5-FU, Leucovorin, Oxaliplatin, Docetaxel) – new standard.
  • ECF/ECX (Epirubicin, Cisplatin, 5-FU or Capecitabine) – traditional regimen.
  • Duration: Usually 2–4 cycles over 6–8 weeks.

Neoadjuvant Chemoradiotherapy (in selected cases)

  • Gives chemotherapy together with aimed radiation.
  • Utilized primarily for gastroesophageal junction (GEJ) or Siewert type I/II tumors.
  • Regimen example: CROSS trial – Carboplatin + Paclitaxel + Radiotherapy.

Gastric cancer chemotherapy before surgery

Neoadjuvant chemotherapy is chemotherapy administered prior to surgery in patients with locally advanced but resectable gastric cancer. It enhances outcomes by downsizing the tumor, enhancing the likelihood of complete surgical resection, and treating early possible micrometastases.

Why Chemotherapy Before Surgery?

  • Reduces the tumor to enhance the effectiveness of surgery
  • Enhances R0 resection rates (complete removal of the tumor)
  • Treats microscopic dissemination before it is clinically apparent
  • Enhances survival over surgery alone

What is neoadjuvant therapy?

Neoadjuvant treatment is treatment provided prior to the primary (main) treatment, most often surgery, with the aim of enhancing the efficacy of that primary treatment.

Role of Neoadjuvant Therapy:

  • Shrink the tumor prior to surgery
  • Make previously inoperable tumors operable
  • Enhance opportunity for complete resection of the tumor (R0 resection)
  • Treat microscopic cancer early
  • Evaluate response to treatment (assist in directing additional therapy)

Benefits of neoadjuvant therapy in stomach cancer

Neoadjuvant treatment—typically chemotherapy before operation—is an integral component of treatment for locally advanced gastric cancer (Stage IB to III). It has numerous clinical and survival advantages.

Tumor Reduction

  • Decreases tumor size prior to operation
  • Makes unresectable or marginal tumors resectable
  • Makes R0 resection (with margins) more feasible

Improved Surgical Outcome

  • Permits less radical operations
  • Makes laparoscopic or organ-sparing surgery more likely in selected patients
  • Increases effectiveness and safety of surgery

Early Treatment of Micrometastases

  • Destroys micro-cancer cells that already might have spread (but cannot be seen on scans)
  • Decreases chance of distant recurrence following surgery

Enhanced Long-Term Survival

  • Several studies (e.g., MAGIC, FLOT4) demonstrate enhanced overall survival (OS) and disease-free survival (DFS) when chemotherapy is administered before and after surgery versus surgery alone

Tumor Biology Assessment

  • Aids in assessment of how aggressive the tumor will be based on its responsiveness to treatment
  • Poor response can result in altered postoperative treatment

Individualized Postoperative Treatment

  • Adjuvant therapy is determined by response to neoadjuvant therapy
  • Good responders can have same chemo given post-op; non-responders can require alternative plans or clinical trials

Diagnostic & Planning Benefit

  • Interval before neoadjuvant therapy provides time for:
  • Improved staging with new imaging
  • Laparoscopy to identify occult metastasis
  • Preparation of nutrition prior to major surgery

Gastric cancer treatment guidelines

Treatment of gastric cancer is based on stage, site, histology, and patient status. Guidelines differ minimally by country (e.g., NCCN, ESMO, Japanese, Indian guidelines), but are otherwise similar.

Diagnosis & Initial Workup

Pre-treatment:

  • Upper GI endoscopy with biopsy
  • CT chest, abdomen, pelvis ± PET-CT
  • Diagnostic laparoscopy (particularly in locally advanced disease)
  • HER2 testing, PD-L1, MSI/MMR, and EBV status (advanced/metastatic disease)

Stage-Wise Treatment Approach

Stage 0–IA (Early-stage)

  • Endoscopic resection (EMR/ESD) for highly early tumors (T1a, <2cm, well-differentiated, no ulceration)
  • Otherwise, gastrectomy + D1/D2 lymphadenectomy

Stage IB–III (Locally advanced, resectable)

Preferred Approach:

  • Perioperative Chemotherapy + Surgery
  • Chemotherapy before and after surgery (Neoadjuvant + Adjuvant)
  • FLOT regimen preferred (NCCN/ESMO)
  • 4 cycles before + 4 cycles after surgery

Surgery:

  • Subtotal or total gastrectomy + D2 lymph node dissection

Alternative (if perioperative chemo not possible):

  • Surgery first, adjuvant chemotherapy afterwards (e.g., XELOX or S-1 for stage II/III)

Stage IV (Unresectable or metastatic)

  • Systemic therapy (palliative intent):
  • First-line: Fluoropyrimidine + Platinum ± Trastuzumab (if HER2+)
  • Emerging options: Immunotherapy (e.g., nivolumab) in PD-L1 positive or MSI-high tumors
  • Palliative radiation or stenting for symptom control

Neoadjuvant vs adjuvant therapy in cancer

Neoadjuvant Therapy

  • Neoadjuvant therapy is given prior to surgery. 
  • Neoadjuvant therapy is intended to shrink the tumor and enhance the efficacy of the surgical procedure. 
  • The objective of neoadjuvant therapy is to make the tumor smaller, downstage the disease, and facilitate surgery to be easier or more effective. 
  • It also aids in the treatment of possible micrometastases early. 
  • Neoadjuvant therapy may render inoperable tumors operable or permit less invasive surgery, e.g., to spare more of the organ or prevent disfigurement. 
  • Neoadjuvant therapy may also enhance the chances of a complete (R0) resection. 
  • The benefit of neoadjuvant therapy is that it provides an opportunity for assessment of tumor response to treatment prior to surgery. 
  • A favorable response can inform subsequent treatment strategies or suggest a more favorable prognosis. 
  • Neoadjuvant therapy risks postponing surgery in case of adverse side effects or non-response to the treatment. 
  • It also requires meticulous follow-up to prevent progression of the tumor during treatment.

Adjuvant Therapy

  • Adjuvant therapy is administered following surgery. 
  • Adjuvant therapy is used to kill any residual microscopic cancer cells that may be left following removal of the tumor by surgery. 
  • The aim of adjuvant therapy is to prevent recurrence by eradicating residual cancer cells that were not visible or resectable at surgery. 
  • Adjuvant therapy does not influence the surgical strategy since it is administered after surgery depending on the final pathology report. 
  • Adjuvant therapy, however, is determined by the results of surgical pathology, which entail tumor stage, involvement of lymph nodes, and margins. 
  • Adjuvant therapy can be poorly tolerated after surgery, particularly if the patient undergoes a long postoperative course, has complications, or has compromised immunity following surgery.

Best hospital for gastric cancer in India

Stomach cancer surgery after chemo

In advanced gastric cancer in the stomach (Stage IB–III), chemotherapy is usually administered ahead of surgery to reduce the tumor and enhance surgical success. This is termed neoadjuvant chemotherapy, and subsequent surgery is a key factor in total cancer removal and cure.

Step-by-Step: What Happens After Chemo

Response Evaluation

Following 2–3 months of chemotherapy (typically 4 cycles, e.g., FLOT regimen), physicians will:

  • Repeat CT scans or PET-CT to measure tumor reduction
  • Occasionally repeat diagnostic laparoscopy
  • Check blood tests and overall health
  • If the tumor has decreased or stayed the same and there's no new spread ➝ surgery is planned.

Type of Surgery

The type of gastrectomy varies based on the location and size of the tumor:

  • Distal (lower stomach): Distal/Subtotal Gastrectomy
  • Proximal (upper stomach): Proximal Gastrectomy
  • Extensive/entire stomach: Total Gastrectomy
  • All surgeries involve a D2 lymph node dissection, which removes lymph nodes around large arteries to minimize recurrence risk.

Hospital Recovery

  • Hospital stay: typically 5–10 days
  • Early mobilization, IV fluids, and resumption of oral intake in a step-by-step manner
  • Follow-up for complications: bleeding, leakage, infections
  • Nutritional support: soft diet, occasionally with feeding jejunostomy

Post-Surgery Therapy (Adjuvant Chemo)

  • Patients undergo adjuvant chemotherapy after recovery, typically 4–6 weeks later, usually the same treatment as pre-surgery (e.g., 4 additional FLOT cycles), if the patient remains fit.

Nutritional & Long-Term Follow-Up

  • Total gastrectomy: lifetime injections of vitamin B12

Follow-up every 3–6 months:

  • Physical examination
  • Imaging (CT scans)
  • Blood tests
  • Counselling for diet to avoid weight loss and dumping syndrome

Neoadjuvant chemoradiotherapy for gastric cancer

Neoadjuvant chemoradiotherapy (CRT) is the use of chemotherapy and radiation therapy preoperatively to enhance treatment efficacy in locally advanced gastric cancer. Although neoadjuvant chemotherapy alone (e.g., FLOT) is currently the worldwide standard, CRT is an option in certain situations—particularly gastroesophageal junction (GEJ) cancers or maximal downstaging as an objective.

When Is It Used?

Neoadjuvant chemoradiotherapy is generally reserved for:

  • Locally advanced GE junction cancer tumors (Type II or III)
  • T3/T4 or node-positive
  • Tumors of borderline resectability
  • Cases in which the tumor involves adjacent organs
  • Selected patients within clinical trials

Chemoradiotherapy Regimens

One regimen that is commonly used has:

Chemotherapy:

  • Simultaneous with radiation
  • Options: 5-FU or capecitabine ± platinum (cisplatin or oxaliplatin)

Radiation therapy:

  • 45 Gy in 25 fractions during 5 weeks
  • Focused on the primary tumor and regional lymph nodes

Success rate of neoadjuvant therapy in cancer

Neoadjuvant treatment (pre-operative treatment) has been highly successful in many types of cancer. Success, however, is highly variable based on the type of cancer, the stage, biological behavior, and neoadjuvant therapy type (chemotherapy, radiotherapy, chemoradiotherapy, or targeted/immunotherapy).

Approximate Success Rates by Cancer Type

  • Breast Cancer: 60–80%    
  • Rectal Cancer: 50–70%    
  • Esophageal/GEJ Cancer: 50–65%    
  • Gastric Cancer: 40–60%    
  • Non-Small Cell Lung Cancer: 40–60%    
  • Pancreatic Cancer: 30–50%    
  • Bladder Cancer: 40–60%    
  • Sarcomas (limb): 60–70%    

Stage 3 gastric cancer treatment options    

Stage 3 gastric (stomach) cancer indicates that the cancer has extended deeply into the stomach wall and regional lymph nodes, but not to distant sites. It is advanced locally and, with intense treatment, is potentially curable. Multimodal therapy — chemotherapy, surgery, and, in some cases, radiation — is the standard treatment.

Neoadjuvant Chemotherapy (Pre-op)

Why used:

  • Reduces the tumor
  • Enhances the probability of cure (R0 resection)
  • Treats early micrometastatic disease
  • Standard regimen:
  • FLOT (5-FU, Leucovorin, Oxaliplatin, Docetaxel) — 4 cycles prior to surgery
  • Alternative: ECF/EOX regimens in case FLOT is not indicated

Surgery (Gastrectomy)

Following good chemo response and if imaging is negative for distant disease, patients are treated with curative surgery:

  • Lower stomach: Subtotal/distal gastrectomy
  • Upper/whole stomach: Total gastrectomy
  • Always with D2 lymph node dissection (removal of regional lymph nodes)

Adjuvant Chemotherapy (After Surgery)

Why it's done:

  • Kills microscopic remaining cancer
  • Decreases recurrence risk
  • Typically the same regimen as pre-operatively (e.g., 4 additional cycles of FLOT)
  • Can be omitted if the patient is post-operative unfit

Chemoradiotherapy (Selective Use)

Can be done post-surgery, particularly if:

  • Margins are involved (R1 resection)
  • Large lymph node burden
  • Chemotherapy alone is not an option
  • Regimen: Capecitabine or 5-FU with concurrent radiotherapy (45–50.4 Gy)

Targeted Therapy & Immunotherapy (Limited Role in Stage 3)

  • HER2-positive cancers: Trastuzumab (Herceptin) is generally reserved for metastatic disease, not routine in Stage 3
  • Immunotherapy (e.g., nivolumab): Under investigation in trials; can be added after surgery and chemo in certain patients (particularly MSI-high or PD-L1 positive)

Nutritional and Supportive Care

  • Nutritional support (secondary to decreased intake following gastrectomy)
  • Vitamin B12 supplementation (lifetime after total gastrectomy)
  • Multidisciplinary team: oncologist, surgeon, dietitian, psychologist

Gastric cancer survival rate after treatment

The prognosis or survival rate for stomach (gastric) cancer relies considerably on various factors, including the stage of cancer at diagnosis, location of the tumor, response to treatment, extent of surgical resection (R0), and overall health of the patient.

The following is a description of post-treatment survival rates, particularly after surgery and chemotherapy.

General 5-Year Survival Rates by Stage (After Treatment)

  • Stage I: 60–90%    
  • Stage II: 40–60%    
  • Stage III: 20–50%    
  • Stage IV: <10–20%    

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