Spotlight on HER2-Positive Gastric Cancer: Using Biomarker Testing to Inform Treatment Decisions

Not real HCPs or patients

The last few decades of cancer care have witnessed powerful breakthroughs in targeted therapies that are tailored to each patient’s unique needs.¹ For a disease like gastric cancer, which develops in the stomach and is the fifth most common cancer, biomarker testing has emerged as a crucial piece of the puzzle helping to improve patient outcomes.^2–4

Many people with early stage gastric cancer experience little to no symptoms, which often results in diagnosis at an advanced stage.⁵ Identifying the disease later typically limits treatment options and is associated with poor prognosis.^6,7 In 2025, more than 30,000 people are expected to be diagnosed with gastric cancer in the United States.⁸ Gastric cancer deaths in the US have been steadily declining in the last decade – a trajectory that we hope to continue moving forward.⁹

Unlocking the HER2 Biomarker Connection in Gastric Cancer

Biomarker testing is a method to look for certain features in cancer cells, such as genes or proteins.¹⁰ These features, also known as tumor markers, can provide information about a cancer, for example, how fast it might grow, whether it can be treated with a targeted therapy or if the cancer is responding to treatment.¹¹

One common tumor marker is human epidermal growth factor receptor 2 (HER2), a type of growth-promoting protein found on the surface of multiple types of cancer cells, including gastric cancer.^12,13 When cells produce too much HER2 protein, they can become cancerous.¹⁴ Approximately one in five gastric cancers are considered HER2-positive, meaning they have larger than normal amounts of HER2 protein.¹⁴ Having too many copies of the HER2 protein can cause cancers to grow quickly and metastasize (spread) to other parts of the body.¹⁵ A HER2-positive diagnosis is a challenging one for patients because the disease is aggressive, with increased risk of recurrence and often, worse outcomes.^12,14 But there’s also hope – a patient with HER2-positive gastric cancer may have alternative treatment options in addition to chemotherapy, including targeted therapies.¹⁶

How Biomarker Testing Impacts Diagnosis and Treatment

To determine if a patient’s cancer is HER2-positive, oncologists can collect a small sample of the cancer tissue.¹⁷ The sample will be sent to a special lab where it can be tested for biomarkers, including HER2. The lab will then share the results that show which biomarkers are present, and the treating oncologist will identify any treatment options that may work based on those findings.^10,17

For patients with gastric cancer, biomarker testing can empower them with more information about their diagnosis and pave the way for potential treatment options.³

“Biomarker testing is critically important in helping oncologists determine which treatment is most appropriate for someone,” said Aki Smith, founder of Hope for Stomach Cancer, a US-based advocacy organization. “If you have been diagnosed with gastric cancer, especially if you’re newly diagnosed, I urge you to talk with your doctor about having biomarker testing for your tumor. Understanding whether your cancer is HER2-positive or has other biomarkers can open the door to treatment options that may make a real difference.” Learn more about gastric cancer and biomarkers here.

HER2 Expression in Gastric Cancer: Next Steps for Treatment

Personalizing treatment for HER2-positive gastric cancer opens the door for treatments that disrupt the mechanisms enabling the tumor to grow.¹⁶ Patients with previously untreated HER2-positive advanced gastric cancer can be treated with a HER2-targeting medicine in addition to chemotherapy.^16,18

AstraZeneca’s Commitment to Patients With HER2-Positive Gastric Cancer

At AstraZeneca, we are leading a revolution in oncology, focused on developing and delivering life-changing medicines for patients with gastric cancer – including innovative targeted therapies designed to meet their specific needs. HER2 testing is of vital importance in understanding a patient’s individual gastric cancer diagnosis and in informing treatment decisions so they can experience the best possible outcome.

For patients, access to clear, actionable information can make all the difference. Raising awareness about the importance of biomarker testing helps patients understand their disease on a deeper level – creating opportunities for more personalized and potentially more effective treatment options. Through education, advocacy and innovation, we’re working to ensure that every patient feels informed, supported and empowered to make decisions that lead to longer, fuller lives. Because in the end, it’s not just about treating cancer – it’s about transforming outcomes and restoring hope.

To learn more about gastric cancer, read more here.