Why that heartburn might be stomach cancer – and how salty food increases the risk
Experts say it often goes undetected because symptoms are similar to regular digestive issues. And if you love salted fish and pickled vegetables, there’s a warning for you, too.
If you have that occasional burning sensation in the chest after a meal, chances are, you’d chalk it up to over-eating and get on with life.
But for Chan Yee Soo, 69, the persistent heartburn and gastric reflux he had for a few months five years ago were too ominous to ignore.
Through gastroscopy, Chan was found to have a 5cm tumour in his stomach – which turned out to be stage three cancer. The then-64-year-old worksite supervisor underwent surgery to remove his entire stomach and the surrounding lymph nodes, and received three cycles of chemotherapy. But that wasn’t the last of the cancer.
Three and a half years later, Chan developed recurrent abdominal pain. The cancer had returned, this time, as stage four cancer in the peritoneum, a thin layer of tissue that covers the outer surface of the organs in the abdomen and the inner surface of the abdominal wall. The widespread growths were invading into his intestines and the worst was the obstruction in the colon.
Instead of cutting out the tumours as it would remove too much of Chan's intestines, the surgeon created a bypass around the obstruction in his colon to allow food to pass through. Chan is currently receiving immunotherapy combined with chemotherapy to target the tumours.
Chan's account, as shared by the National Cancer Centre Singapore (NCCS), is typical as stomach cancer doesn’t register as well as colon or breast cancer on people’s minds when it comes to the “C” word.
To find out how you can protect yourself, CNA Lifestyle spoke to the experts to debunk some myths.
MYTH #1: STOMACH CANCER IS LIMITED TO THE STOMACH AND IS VERY RARE
According to the 2019 report from the Singapore Cancer Registry, stomach cancer is the top five most common cause of cancer death in Singapore. Between 2013 and 2017, it claimed over 1,500 lives.
Stomach cancer is a disease in which malignant cells form in the lining of the stomach. But it doesn’t stop there. “Stomach cancer most commonly spreads into the abdominal cavity,” said Clinical Assistant Professor Matthew Ng, a senior consultant with NCCS's Division of Medical Oncology. In patients who have had their stomachs removed, the cancer normally comes back in the peritoneum.
More worryingly, its signs are often overlooked. By the time patients suspect something is amiss, as in Chan’s situation, the cancer may have progressed to a late stage. In fact, more than two thirds of patients are diagnosed at stage three or four out of the four stages, according to the Singapore Cancer Society.
MYTH #2: YOU’LL KNOW IT’S STOMACH CANCER BECAUSE IT’S EXCRUCIATING
Unfortunately, one reason for the late detection is that stomach cancer tumours generally cause symptoms that get dismissed as regular digestive issues. It can present as a persistent pain in the upper abdomen, which you may mistake for indigestion – or in Chan’s case, heartburn and acid reflux.
But there are also more serious signs, said Clinical Asst Prof Ng, that include vomiting blood, passing black stools of digested blood, or persistent vomiting after eating because of the tumour’s blockage.
“If the tumour is large, a lump can be felt in the upper abdomen. More general symptoms like fatigue due to anaemia and unexplained weight loss can be caused by stomach cancer”. He added that if the cancer has spread to the abdominal cavity, “it can cause swelling of the abdomen due to fluid accumulation”.
MYTH #3: YOU’RE BOUND TO GET IT IF YOU HAVE A FAMILY HISTORY
If you’re looking at genetic connections, only up to 10 per cent of stomach cancer cases are hereditary, said Assistant Professor Joanne Ngeow, the head of Cancer Genetics Service and a senior consultant with NCCS’s Division of Medical Oncology.
“However, the exact cause for familial stomach cancer is not always known. Shared environmental factors, or a combination of genetic and environmental factors, may be responsible for some familial cases of stomach cancer,” she said. In particular, changes in the CDH1 gene can predispose you to a “much higher risk of gastric cancers than the general population”.
Cancers of the stomach and colon can sometimes be traced to genetic conditions such as Lynch syndrome or Li Fraumeni syndrome, said Asst Prof Ngeow.
“However, not all people with a genetic predisposition to develop stomach cancer, or a known hereditary cancer syndrome, will develop stomach cancer. Genetic testing can be done to look for the gene mutations that can cause some inherited cancer syndromes.”
Other than a family history, age is another factor. Between 2013 and 2017, 23.2 per cent of stomach cancer occurred in those aged 80 and above, said Clinical Asst Prof Ng.
MYTH #4: PRESERVATIVES IN FOOD ARE GIVING PEOPLE STOMACH CANCER
Interestingly, it’s the salt used to preserve food, such as salted fish and pickled vegetables, that’s the key.
“There is strong evidence that consuming food preserved by salting increases the risk for stomach cancer,” said dietitian Lee Miaw Sim from Singapore General Hospital’s Department of Dietetics, citing the Continuous Update Project (CUP) by World Cancer Research Fund International.
This may explain why the Chinese population in Singapore, which typically includes salt-preserved food in their diet, has the highest risk of developing stomach cancer than the Malays and Indians, according to the Singapore Cancer Registry.
“There is also some evidence suggesting that consumption of processed meat as well as grilled or barbecued meat and fish, might increase the risk for stomach cancer but the evidence is limited,” said Lee.
How does salt damage the stomach? It hurts the stomach mucosal lining and leads to inflammation and cellular damage. This, in turn, makes it easy for the ulcer-inducing bacteria Helicobacter pylori to colonise the stomach, which according to Lee, is the strongest known risk factor for stomach cancer.
“Based on a report by World Cancer Research Fund 2009, approximately 14 per cent of stomach cancer cases could be avoided through reducing salt intake to less than the recommended daily amount of intake, which is equivalent to about one teaspoon,” she said.
You’re also better off avoiding alcohol “as there is strong evidence that drinking alcohol increases the risk for stomach cancer”, she added.
MYTH #5: IF YOU HAVE STOMACH CANCER, CUT OUT SUGAR SO YOU WON’T FEED THE CANCER
Because cancer cells multiply quickly, they require a lot of energy or glucose to grow. And that is where the myth that sugar fuels cancer comes from: Cut out sugar from your diet and it’ll stop the cancer from developing.
It doesn’t work that way or vice versa, said Clinical Asst Prof Ng. “Consuming more sugar has not been shown to make cancers grow faster in patients. On the another hand, cutting calorie intake excessively can be detrimental to patients who are already suffering from weight loss from their cancer as they may feel more tired and less able to cope with their treatment.”
MYTH #6: IF THE CANCER DOESN’T KILL YOU, REMOVING YOUR STOMACH WILL
Chan’s story earlier on is proof that stomach cancer is not a death sentence, said Clinical Asst Prof Ng. In fact, a month after removing his stomach, Chan was able to start eating solid food, including rice and meat. According to him, patients who have undergone stomach removal can even eat curry, but in moderation. However, they’ll have to steer clear of raw food, food that is too sweet or has too much fibre as well as anything that is difficult to swallow as it can cause indigestion.
Moreover, not every patient will require a complete removal of the stomach. “The size and location of the tumour is important and it will dictate how much of the stomach needs to be removed to get complete clearance of the tumour,” said Clinical Asst Prof Ng.
What is definitely affected though is the amount of food patients can, well, stomach, said Lee. “The stomach will not be able to hold as much as it did before surgery. Patients may feel full faster than they did before surgery.” To get around the situation, she recommended patients to eat small and frequent meals up to six times throughout the day – and to eat slowly and chew well for easier digestion.
“Wait around one hour after a meal before drinking liquids. This will allow patients to eat enough solid food without getting too full or bloated, and reduce the risk for dumping syndrome,” said Lee, referring to the group of symptoms such as nausea, vomiting and abdominal pain that occur when food moves too quickly into the small intestine.
The other concern is the lack in certain nutrients post-surgery. “Some patients may become deficient in nutrients such as iron, calcium, folate and Vitamins D and B12, as their body may be unable to absorb these nutrients as easily as before from food,” said Lee, who recommended checking with the doctor for supplements.