Gastric cancer treatment has evolved significantly in recent years, offering patients more options than ever before to fight this disease. From surgical procedures that can cure early-stage cancer to innovative immunotherapies showing promise in advanced cases, the landscape of stomach cancer care continues to expand with both established treatments and experimental approaches being tested in clinical trials around the world.

How Modern Medicine Approaches Stomach Cancer

When someone receives a diagnosis of gastric cancer, the path forward depends heavily on several key factors. The stage of the cancer, meaning how far it has spread from its original location, plays a crucial role in determining which treatments will be most effective. Additionally, the specific characteristics of the tumor, the patient’s overall health status, and even the location of the cancer within the stomach all influence the treatment plan that doctors recommend.^[1]

Treatment goals vary depending on the disease stage. For cancers caught early, when they remain confined to the stomach lining or haven’t spread far beyond it, the aim is often curative treatment—meaning doctors work to eliminate the cancer completely and prevent it from returning. In more advanced cases, where the cancer has spread to distant organs, treatment focuses on controlling the disease’s progression, managing symptoms, and improving quality of life for as long as possible.^[8]

Medical societies and cancer organizations have established standard treatment protocols based on decades of research and clinical experience. These guidelines help ensure that patients receive evidence-based care regardless of where they’re treated. At the same time, ongoing research through clinical trials continues to explore new therapies and treatment combinations that might offer better outcomes than current standards. This means that patients diagnosed today have access not only to proven treatments but also to cutting-edge experimental approaches that could become tomorrow’s standard of care.^[10]

Standard Treatment Approaches for Gastric Cancer

Surgery: The Foundation of Curative Treatment

Surgery remains the cornerstone of treatment for patients with stomach cancer that hasn’t spread to distant parts of the body. The type of surgical procedure depends primarily on where the tumor is located within the stomach and how extensively it has grown. A gastrectomy, which means the surgical removal of part or all of the stomach, is the main operation performed for gastric cancer.^[9]

In a subtotal gastrectomy, surgeons remove the portion of the stomach containing the cancer along with nearby lymph nodes and sometimes parts of other nearby tissues or organs. This procedure is typically used when the tumor is located in the lower part of the stomach. The surgeon then reconnects the remaining stomach to the small intestine, allowing the patient to continue eating and digesting food, though often in smaller quantities than before.^[9]

A total gastrectomy involves removing the entire stomach. This more extensive surgery is necessary when cancer is located in the upper part of the stomach or has spread throughout the organ. After the stomach is removed, surgeons connect the esophagus directly to the small intestine, creating a new pathway for food. While this dramatically changes how digestion works, patients can still eat and maintain nutrition with proper dietary adjustments.^[9]

An essential part of stomach cancer surgery is lymphadenectomy—the removal of lymph nodes near the stomach. Cancer cells often spread to these small, bean-shaped structures that are part of the body’s immune system. By removing them, surgeons aim to eliminate any cancer that may have begun spreading beyond the stomach itself. The extent of lymph node removal varies, but comprehensive lymphadenectomy is generally recommended to improve patient outcomes.^[5]

Recovery from gastric surgery can take several weeks and requires significant adjustments. Patients often need to eat smaller, more frequent meals because they have less stomach capacity. Working closely with a dietitian helps ensure adequate nutrition during the healing process and beyond.^[22]

Chemotherapy: Using Drugs to Attack Cancer Cells

Chemotherapy involves using powerful medications that kill rapidly dividing cancer cells or stop them from growing. In gastric cancer treatment, chemotherapy serves multiple purposes depending on when it’s given. When administered before surgery, called neoadjuvant chemotherapy, these drugs aim to shrink the tumor, making it easier to remove and reducing the amount of tissue that needs to be taken out. This approach may also kill cancer cells that have spread to nearby areas but aren’t yet visible.^[9]

After surgery, patients may receive adjuvant chemotherapy to eliminate any remaining cancer cells that weren’t removed during the operation. Even when surgeons believe they’ve removed all visible cancer, microscopic disease may remain, and chemotherapy serves as insurance against recurrence. Studies have shown that combining surgery with chemotherapy improves survival rates compared to surgery alone.^[11]

In cases where the cancer is too advanced for surgery or has spread to distant organs, chemotherapy becomes the main treatment. Here, the goal shifts from cure to control—slowing the cancer’s growth, shrinking tumors to relieve symptoms, and extending survival. Common chemotherapy regimens for gastric cancer combine several drugs that work together to attack cancer cells through different mechanisms.^[10]

Chemotherapy is typically given in cycles, with treatment periods followed by rest periods to allow the body to recover. For stomach cancer, treatment often occurs every two weeks and may continue for several months. The specific drugs used and the duration of treatment depend on the cancer’s characteristics and how well the patient tolerates the medication.^[8]

Side effects are common with chemotherapy because these drugs affect not only cancer cells but also healthy cells that divide rapidly, such as those in the digestive tract, hair follicles, and bone marrow. Patients may experience nausea, vomiting, fatigue, hair loss, increased risk of infection, and changes in appetite. However, modern supportive care medications can significantly reduce many of these side effects, and doctors work closely with patients to manage symptoms and maintain quality of life during treatment.^[15]

Radiation Therapy: Targeting Cancer with High-Energy Beams

Radiation therapy uses high-energy beams, similar to x-rays but much stronger, to damage cancer cells’ DNA and prevent them from growing and dividing. For gastric cancer, radiation is most commonly delivered as external beam radiation therapy, where a machine outside the body directs radiation beams precisely at the tumor.^[9]

Radiation therapy is sometimes combined with chemotherapy in a treatment approach called chemoradiation. The chemotherapy drugs make cancer cells more sensitive to radiation, enhancing the treatment’s effectiveness. This combination may be used before surgery to shrink tumors or after surgery to eliminate any remaining cancer cells in the surgical area.^[8]

While radiation therapy aims to spare healthy tissue, some side effects can occur because normal cells in the treatment area may also be affected. Patients receiving radiation to the stomach area might experience nausea, diarrhea, fatigue, and skin changes in the treated region. These effects are usually temporary and improve after treatment ends, though some patients may experience longer-lasting digestive changes.^[15]

Targeted Therapies: Precision Attacks on Cancer

Targeted therapies represent a more precise approach to cancer treatment. Unlike chemotherapy, which affects all rapidly dividing cells, targeted therapies focus on specific molecules or pathways that cancer cells rely on to grow and survive. For gastric cancer, several targeted therapies have been approved based on specific characteristics of the tumor.^[10]

Trastuzumab is a monoclonal antibody that targets a protein called HER2, which appears on the surface of some cancer cells. About 10% to 20% of gastric cancers are HER2-positive, meaning they have abnormally high levels of this protein. Trastuzumab binds to HER2 and blocks signals that tell cancer cells to grow and divide. It also helps the immune system recognize and destroy cancer cells. For patients with HER2-positive advanced gastric cancer, adding trastuzumab to chemotherapy significantly improves survival compared to chemotherapy alone.^[13]

Ramucirumab works by a different mechanism. It targets a pathway called VEGF/VEGFR2 that cancer cells use to create new blood vessels. Tumors need blood vessels to deliver nutrients and oxygen as they grow. By blocking this pathway, ramucirumab starves the tumor and slows its growth. This drug is approved for patients with advanced gastric cancer whose disease has progressed despite initial chemotherapy.^[13]

More recently, trastuzumab deruxtecan, an antibody-drug conjugate, has shown remarkable effectiveness in HER2-positive gastric cancer. This medication combines an antibody that targets HER2 with a chemotherapy drug attached to it. The antibody acts like a guided missile, delivering the chemotherapy directly to cancer cells while sparing healthy tissue. This targeted delivery system means potentially stronger anti-cancer effects with fewer side effects than traditional chemotherapy.^[10]

Immunotherapy: Harnessing the Body’s Defense System

Immunotherapy represents one of the most exciting advances in cancer treatment in recent years. These therapies work by helping the patient’s own immune system recognize and attack cancer cells. Normally, the immune system patrols the body looking for abnormal cells, but cancer cells can develop ways to hide from or suppress immune responses. Immunotherapy removes these brakes, allowing the immune system to do its job.^[13]

Checkpoint inhibitors are the main type of immunotherapy used for gastric cancer. These drugs target proteins like PD-1 or PD-L1 that cancer cells use to evade immune detection. When cancer cells display PD-L1 on their surface and it binds to PD-1 on immune cells, it essentially tells the immune system to stand down. Checkpoint inhibitors block this interaction, reactivating immune cells so they can attack the cancer.^[13]

Several checkpoint inhibitors have been approved for gastric cancer, including pembrolizumab, nivolumab, and dostarlimab. These medications work particularly well in tumors with certain characteristics. Cancers with high levels of PD-L1 expression or those with microsatellite instability (MSI-high) or DNA mismatch repair deficiency (dMMR) are more likely to respond to checkpoint inhibitors. These biomarkers indicate that the tumor may be more visible to the immune system or more vulnerable to immune attack.^[13]

Immunotherapy side effects differ from those of chemotherapy. Because these drugs activate the immune system, they can sometimes cause the immune system to attack normal tissues, leading to inflammation in various organs. Common side effects include fatigue, skin rashes, diarrhea, and changes in hormone levels. While most side effects are manageable, some can be serious and require prompt medical attention.^[13]

Procedures for Managing Symptoms and Complications

When stomach cancer causes blockages that prevent food from passing normally through the digestive tract, several procedures can help relieve symptoms even if they don’t cure the cancer. Endoluminal stent placement involves inserting a small, expandable tube through an endoscope to hold open a blocked passage, allowing patients to swallow and eat more comfortably. Similarly, endoluminal laser therapy uses a laser attached to an endoscope to open blocked areas by vaporizing tumor tissue.^[9]

Endoscopic mucosal resection is a procedure that can treat very early-stage gastric cancer that’s confined to the innermost lining of the stomach. Using an endoscope, doctors can remove these early tumors without the need for major surgery, offering a less invasive option for carefully selected patients.^[9]

Innovative Treatments Being Tested in Clinical Trials

Clinical trials are research studies that test new treatments or new ways of using existing treatments. They progress through several phases, each designed to answer specific questions about a therapy’s safety and effectiveness. For patients with gastric cancer, participating in a clinical trial may provide access to promising new treatments before they become widely available.^[10]

Next-Generation Anti-HER2 Therapies

Building on the success of trastuzumab, researchers have developed several new ways to target HER2 in gastric cancer. Trastuzumab deruxtecan, mentioned earlier as an approved therapy, emerged from clinical trials that showed it could benefit patients whose cancer had progressed despite previous HER2-targeted treatments. This antibody-drug conjugate works like a smart bomb—the antibody portion finds HER2-positive cancer cells, and then releases chemotherapy directly into those cells.^[10]

Clinical trials have shown that trastuzumab deruxtecan can shrink tumors in a significant percentage of patients with HER2-positive gastric cancer, even in those who had already received multiple prior treatments. The response rates in some studies exceeded 40%, meaning more than four out of ten patients experienced tumor shrinkage. These encouraging results have made this drug a valuable option for HER2-positive disease.^[10]

Other anti-HER2 agents, including disitamab vedotin, are being tested in clinical trials primarily conducted in Asia. These drugs use similar antibody-drug conjugate technology but may have different properties that could offer advantages for certain patients. Phase II and Phase III trials are evaluating how these new agents compare to existing treatments and whether they can extend survival further.^[10]

Expanding Immunotherapy Options

While checkpoint inhibitors have already changed treatment for some gastric cancer patients, researchers are working to expand their benefits to more people. Current clinical trials are testing immunotherapy in earlier stages of disease, including in the perioperative setting—meaning before and after surgery for patients with localized gastric cancer. The hope is that using immunotherapy at earlier stages might prevent recurrence and improve cure rates.^[10]

Combinations of different immunotherapy drugs are also being explored. Some trials test combinations of two checkpoint inhibitors that target different parts of the immune system, potentially creating a stronger anti-cancer response. Other studies combine immunotherapy with targeted therapies or chemotherapy, based on evidence that these combinations might work synergistically—meaning their combined effect is greater than either treatment alone.^[10]

Researchers are particularly interested in understanding which patients are most likely to benefit from immunotherapy. Clinical trials are investigating additional biomarkers beyond PD-L1 and MSI status that might predict response. This research aims to personalize immunotherapy selection, ensuring that each patient receives the treatment most likely to help them while avoiding unnecessary side effects from treatments unlikely to work.^[10]

CAR T Cell Therapy: Engineering Immune Cells

Chimeric antigen receptor (CAR) T cell therapy represents an even more personalized form of immunotherapy. In this approach, doctors collect a patient’s own immune cells called T cells, genetically engineer them in a laboratory to recognize specific proteins on cancer cells, and then infuse the modified cells back into the patient. These engineered T cells can then seek out and destroy cancer cells throughout the body.^[13]

For gastric cancer, researchers are developing CAR T cells that target proteins found on stomach cancer cells. Early-phase clinical trials (Phase I) are testing the safety of these approaches and identifying the best target proteins. Two proteins that have shown promise as targets are NY-ESO-1 and MAGE-3, which appear on some gastric cancers but not on most normal tissues. Studies have detected immune responses to NY-ESO-1 in some gastric cancer patients, suggesting this protein might be a useful target for CAR T cell therapy.^[13]

CAR T cell therapy is complex and currently being tested primarily at specialized cancer centers. The process requires sophisticated laboratory facilities and expertise in cellular therapy. While still experimental for gastric cancer, this approach has shown remarkable success in certain blood cancers, spurring hope that it might eventually benefit solid tumor patients as well.^[13]

Novel Targeted Therapies and Molecular Approaches

As scientists learn more about the genetic changes that drive gastric cancer, they identify new potential targets for therapy. Advanced molecular diagnostic techniques can now analyze a tumor’s complete genetic profile, revealing mutations or abnormalities that might be targeted with specific drugs. This approach, called precision medicine or personalized medicine, tailors treatment to the unique characteristics of each patient’s cancer.^[10]

Clinical trials are testing drugs that target various molecular pathways involved in cancer growth. For example, some gastric cancers have abnormalities in genes called FGFR (fibroblast growth factor receptor), and drugs targeting these receptors are being evaluated. Other trials focus on cancers with mutations in a gene called KRAS or amplifications of genes like MET. Each of these molecular alterations potentially represents a vulnerability that targeted drugs can exploit.^[10]

These trials typically enroll patients whose tumors have been tested and found to have the specific molecular target the drug is designed to attack. This biomarker-directed approach increases the likelihood that enrolled patients will benefit, making trials more efficient and sparing patients from receiving treatments unlikely to help them.^[10]

Combination Strategies and Perioperative Treatment

One of the most active areas of research involves testing whether adding immunotherapy or targeted therapy to standard perioperative chemotherapy can improve outcomes for patients with locally advanced gastric cancer. Traditional treatment for these patients involves chemotherapy before and after surgery, and several clinical trials are now investigating whether adding checkpoint inhibitors to this regimen enhances effectiveness.^[10]

Phase III trials—the final stage before a treatment can be approved—are comparing standard chemotherapy alone versus chemotherapy plus immunotherapy in the perioperative setting. These large studies involve hundreds of patients and will determine whether the addition of immunotherapy increases cure rates and prevents recurrence. Results from these trials could potentially change the standard of care for patients with operable gastric cancer.^[10]

For patients with advanced gastric cancer, trials are testing novel combinations of immunotherapy with targeted therapies. For instance, some studies combine checkpoint inhibitors with anti-angiogenic drugs (medications that prevent tumor blood vessel formation) or with HER2-targeted therapies in HER2-positive cancers. The rationale is that targeting multiple pathways simultaneously might overcome resistance mechanisms that allow cancer to evade single-agent therapies.^[10]

Understanding Clinical Trial Phases

Phase I trials primarily assess safety. These first-in-human studies involve small numbers of patients and focus on determining the appropriate dose of a new drug, identifying side effects, and understanding how the body processes the medication. Phase I trials typically enroll patients with advanced cancer who have already tried standard treatments.^[10]

Phase II trials evaluate effectiveness. If a drug is deemed safe in Phase I, Phase II studies test whether it actually works against cancer. These trials enroll more patients and measure outcomes like how many tumors shrink (response rate) and how long patients live without their cancer worsening (progression-free survival). Phase II trials help researchers decide whether a drug is promising enough to move forward to larger studies.^[10]

Phase III trials compare new treatments to current standards. These large studies randomly assign patients to receive either the new treatment or the current standard treatment, allowing researchers to definitively determine whether the new approach is better. Phase III trial results form the basis for drug approvals by regulatory agencies. These trials often involve multiple hospitals and cancer centers across different countries to enroll enough patients quickly.^[10]

Clinical trials for gastric cancer are being conducted at major cancer centers in the United States, Europe, and Asia, particularly in countries where gastric cancer is more common like Japan, South Korea, and China. Patient eligibility varies by trial but typically depends on factors like cancer stage, previous treatments received, overall health status, and whether the tumor has specific biomarkers targeted by the treatment being studied.^[10]

Most common treatment methods

• Surgery
  • Subtotal gastrectomy removes the cancer-containing portion of the stomach along with nearby lymph nodes and connects the remaining stomach to the small intestine
  • Total gastrectomy removes the entire stomach and connects the esophagus directly to the small intestine
  • Lymphadenectomy removes lymph nodes near the stomach to eliminate potentially spread cancer cells
  • Endoscopic mucosal resection treats very early-stage cancer confined to the stomach lining using an endoscope
  • Endoluminal stent placement inserts an expandable tube to keep blocked passages open, allowing patients to eat
  • Endoluminal laser therapy uses a laser through an endoscope to open gastrointestinal blockages
• Chemotherapy
  • Neoadjuvant chemotherapy is given before surgery to shrink tumors and make them easier to remove
  • Adjuvant chemotherapy is administered after surgery to kill any remaining cancer cells and prevent recurrence
  • Palliative chemotherapy controls cancer growth and symptoms in advanced disease when cure isn’t possible
  • Treatment typically occurs in cycles every two weeks and may continue for several months
• Radiation Therapy
  • External beam radiation therapy directs high-energy beams from outside the body at the tumor
  • Chemoradiation combines radiation with chemotherapy to enhance treatment effectiveness
  • May be used before surgery to shrink tumors or after surgery to eliminate remaining cancer cells
• Targeted Therapy
  • Trastuzumab targets HER2 protein on cancer cells in HER2-positive gastric cancers
  • Trastuzumab deruxtecan combines HER2-targeting antibody with chemotherapy delivered directly to cancer cells
  • Ramucirumab blocks blood vessel formation that tumors need for growth by targeting VEGF/VEGFR2 pathway
  • These treatments work specifically on cancer cells with certain characteristics, sparing more healthy tissue than traditional chemotherapy
• Immunotherapy
  • Checkpoint inhibitors like pembrolizumab, nivolumab, and dostarlimab block proteins that cancer cells use to hide from the immune system
  • Work particularly well in tumors with high PD-L1 expression or microsatellite instability (MSI-high/dMMR)
  • Help the patient’s own immune system recognize and attack cancer cells
  • Being tested in clinical trials for earlier disease stages and in combination with other treatments