Gastric cancer: Understanding the risks, symptoms and treatment options

Gastric cancer, also known as stomach cancer, can develop in any part of the stomach and may spread to other areas of the digestive system and beyond.

Although global cases have steadily declined since the 1950s, gastric cancer still ranks among the deadliest cancers in Singapore. While it was the 8th most common cancer among men and the 10th among women, it remains the 6th leading cause of cancer-related deaths in men and the 7th in women, according to the Singapore Cancer Registry Annual Report 2022.

There is a silver lining – advances in treatment and disease management have broadened options for patients, even at advanced stages.  

UNDERSTANDING THE RISK FACTORS

A key risk factor for gastric cancer is Helicobacter pylori (H. pylori), a bacterial infection of the stomach lining. This bacterium is classified as a Class 1 carcinogen by the International Agency for Research on Cancer – a category reserved for substances with clear evidence of causing cancer. 

“Because of this, managing H. pylori is a priority. If someone is found to have it, doctors will make every effort to eradicate it,” shared Professor Kong Hwai Loong, a medical oncologist at Icon Cancer Centre.

While the most common route of H. pylori transmission remains uncertain, person-to-person spread through faecal-oral transmission is considered the most likely, said Prof Kong. Treatment typically involves using antibiotics and proton pump inhibitors to reduce stomach acid, he added.   

Lifestyle factors also play a role in gastric cancer risk – diets high in alcohol and preserved foods as well as smoking have been associated with a higher risk of developing the disease.  

Excess weight may further compound this risk. Prof Kong explained that a larger waist circumference can raise intra-abdominal pressure, contributing to the development of gastro-oesophageal reflux disease, where stomach acid flows back into the oesophagus. Over time, this chronic reflux can damage the oesophageal lining and lead to Barrett’s oesophagus – a change in cell type that increases the risk of gastroesophageal junction cancer, which occurs where the oesophagus and stomach meet.  

In some cases, individuals may inherit abnormal genes from their parents, making them more susceptible to gastric cancer. 

A SILENT THREAT – RECOGNISING THE SYMPTOMS

Around two out of three gastric cancer patients are diagnosed only at an advanced stage, when surgery is no longer a straightforward option, said Prof Kong. “More often than not, the moment symptoms appear, the boat has left the harbour – that’s the frightening prospect of gastric cancer,” he added.

Common symptoms include dyspepsia, a feeling of unease or discomfort in the upper central abdomen, particularly after meals. However, dyspepsia is also associated with digestive conditions such as reflux, gastritis or gallstone disease. 

“The general rule of thumb is that if symptoms in the upper abdomen don’t improve after two weeks, it’s best to consult a doctor,” said Prof Kong.

Some may experience abdominal fullness, which could be due to fluid buildup when tumour cells invade the inner lining of the abdominal wall, causing irritation. Black, tarry or foul-smelling stools can also be a red flag, as they often signal internal bleeding, shared Prof Kong. 
    
There may also be general symptoms such as loss of appetite and significant weight loss. He pointed out that losing 5 to 10 per cent of one’s body weight within a month could be a cause for concern. “The stomach is the first organ of digestion, so when cancer affects its function, it leads to malnutrition,” he said. 

DIAGNOSIS AND TREATMENT OPTIONS

If a patient presents with gastric symptoms, doctors may begin with a blood test to check for anaemia – a possible sign of gastric cancer, said Prof Kong. This is often followed by a gastroscopy, which allows doctors to examine the stomach lining and take a biopsy for further testing. If cancer is confirmed, imaging scans are used to assess how far the disease has spread – a critical step in planning the most appropriate treatment. 

According to Prof Kong, chemotherapy remains the backbone of treatment for advanced gastric cancer. Recent advances in drug therapies, including immunotherapy and targeted treatments, have improved outcomes when paired with chemotherapy. 

“Studies show that most gastric cancer patients respond well to the combination of chemotherapy and immunotherapy, which trains the immune system to recognise and combat cancer cells more effectively,” Prof Kong said. “The other approach is targeted therapy, which uses drugs that bind to specific molecules on cancer cells, enabling more personalised treatment based on each patient’s unique cancer profile.” 

Whether a patient is suitable for targeted therapy or immunotherapy depends on the presence of biomarkers – biological indicators that help doctors determine the most effective treatment. Key biomarkers include the human epidermal growth factor receptor 2, programmed death ligand 1 and the more recently identified Claudin 18.2. These biomarkers have opened up new options in precision therapy for advanced gastric cancer. 

Comprehensive biomarker testing is important to enable healthcare professionals to match patients with therapies tailored to their specific tumour profile, leading to better treatment outcomes. “Identifying a marker allows us to add a targeted therapy to chemotherapy, improving its ability to shrink tumours and extend survival,” said Prof Kong. 

“For Claudin 18.2, which is present in about 36 per cent of advanced gastric cancers, new targeted therapies that use monoclonal antibodies to bind to this protein and block cancer growth have benefitted patients,” he explained.  

WHY TREATMENT STILL MATTERS IN LATE-STAGE GASTRIC CANCER

For those with advanced gastric cancer, the primary goal is to relieve debilitating symptoms. Many patients experience considerable discomfort – treatment helps bring them as close as possible to their baseline health. “We want the bleeding to stop, the pain to go away and the weight to return,” said Prof Kong. 

Without intervention, few patients survive beyond six months – those months are often marked by worsening symptoms and severe pain, Prof Kong noted. 

The right treatment can help manage disease progression, prevent or delay complications and in some cases, extend survival – even if a cure is not possible. New approaches like targeted therapy may improve both life expectancy and quality of life. 

“Treatment is always worthwhile,” said Prof Kong. “When a patient responds well, they can return to full activity – working, travelling and doing what they love. This renewed sense of normalcy, however long it lasts, can make all the difference.” 

Speak to your attending physician to learn more about gastric cancer and available treatment options. 

This advertorial is intended for disease awareness and educational purposes only. All images are for illustration purposes. Views expressed by the expert are his own and informed by his clinical experience. It does not reference, endorse and/or recommend any product. Information is accurate as of Jun 10, 2025.  

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