Stomach cancer tend to target certain groups of people more than others.
For example, the numbers of this cancer, also called gastric cancer, are so high in Japan and South Korea that both countries have national screening programmes for those aged 50 and 40 years and above respectively.
In Malaysia, consultant clinical oncologist Datuk Dr Mohamed Ibrahim A. Wahid said that Chinese have a three-to-four-times higher risk of developing stomach cancer compared to Malays, who have the lowest risk of developing this cancer.
He added that Indians have an almost similar risk of developing stomach cancer as the Chinese.
This affinity for East Asian ethnicities is likely due to their dietary habits.
Said Dr Ibrahim: “Because the stomach is where you process your food, diet comes into play.
“So there might be a dietary component to this – eating raw fish, eating kimchi or some aspects of the diet that may make it more common.”
Some of the risk factors for stomach cancer include a diet high in salted and pickled foods, as well as processed meats.
Others are being male, smoking, a diet low in fibre, and having a family history of stomach cancer, which may include certain rare inherited conditions like hereditary diffuse gastric cancer and familial adenomatous polyposis.
A risk factor specific to this disease is chronic Helicobacter pylori infection.
“H. pylori can cause stomach ulcers, and sometimes, chronic stomach ulceration can increase the risk of stomach cancer,” said Dr Ibrahim.
However, this common infection can be treated with antibiotics.
While the risk of stomach cancer increases once a person hits their 50s, Dr Ibrahim observed that Malaysians can be affected at a younger age.
“One of the sad things about stomach cancer is that we see them in patients who are quite young in Malaysia, sometimes in their 40s, in their 50s, so they are still quite young,” he said.
What makes it worse is that these patients usually only consult the doctor during the later stages of their disease.
According to the Malaysian National Cancer Registry Report 2007-2011, three-quarters of patients are diagnosed when they are already in stages 3 and 4 of the disease when the cancer has already spread beyond the stomach.
“By and large, stomach cancers are, in the early stage, asymptomatic, that is, they don’t have symptoms.
“As the cancer grows, they might start to get symptoms, and one of the common symptoms is gastric pain – pain in the upper part of the abdomen,” said Dr Ibrahim.
The problem is this pain can be easily mistaken for gastritis, also colloquially known as “gastric”.
Other symptoms include unexplained weight loss; poor appetite; early satiety, where you feel full very quickly after eating only a little; discomfort when eating; and dark or black-coloured stool, which indicates bleeding from the stomach.
“In the later stages, they may have difficulty swallowing, because the upper part of the stomach where the food enters can get blocked; and nausea and vomiting, because of gastric outlet obstruction, where the tumour may block the flow of digested food from the stomach to the duodenum.
“And then if it spreads, you might get bone pain; you might have a distended liver, so you have a distended abdomen; and you might have fluid in your abdomen – a condition called ascites – as the tumour spreads to the local area,” he added.
What usually brings patients in, according to Dr Ibrahim, is severe abdominal pain; fatigue and paleness due to their low haemoglobin levels; loss of appetite; severe unexplained weight loss; and black stool.
The good news, however, is that stomach cancer does not occur very often in our country, with less than five cases in 100,000 people.
“In Malaysia, it is not so common; it is the 10th most common cancer in females, and in males, the eighth most common cancer,” he said.
The first thing Dr Ibrahim does upon suspecting a diagnosis of stomach cancer is to conduct an endoscopy and biopsy.
“A biopsy would confirm whether it is cancer or not.
“And once the biopsy has confirmed that it’s cancer, then we have to do something called staging,” he explained.
“Nowadays, quite commonly, we do a PET (positron emission tomography) scan; if a PET scan is not available, we’d do a CT (computed tomography) scan, and maybe a bone scan as well.
“Then, based on that, you decide what treatment the patient is fit for.”
For those who have stages 1 and 2 cancer, Dr Ibrahim said surgery would be highly recommended as it can be curative.
“If it is stage 3, it’s a combination of chemotherapy, radiotherapy and surgery; stage 4, basically, it is just palliation – controlling the symptoms,” he said.
He noted, however, that there is what he called “the great continental divide” when it comes to the management of stomach cancer in the early stages.
“In Asia, like in Japan and Korea, they believe that surgery is the one and only treatment, and they do very extensive surgery, called D2 surgery.
“And they have very high cure rates – well above 80% with surgery alone.
“Now, in America, because of the RTOG study that they did, they believe in giving the person chemo-radiotherapy first, followed by surgery.
“In Europe, because of the MAGIC study, they do chemotherapy first – make the cancer a bit smaller – then they do surgery, then plus or minus radiotherapy after that,” he said.
He added that as not many Malaysian gastrointestinal surgeons have trained in D2 surgery, most stomach cancer patients here tend to undergo the more simple gastrectomy, which only removes the stomach.
“Because of that, they would normally require additional treatment like chemotherapy and radiotherapy after the surgery to make up for the lack of extensive surgery,” he said.
D2 surgery usually involves the removal of the stomach, spleen, head of the pancreas, omenta (a sheet of fat that covers the abdominal organs) and a significant number of the lymph nodes in the abdomen.
Meanwhile, in stage 4, aside from surgery, chemotherapy and radiotherapy to help control the symptoms of the cancer, there are also the newer targeted therapies.
“So, say for example in stage 4, especially if you have failed the first-line chemo, you can use the targeted agents, drugs like the VEGF inhibitor ramucimurab, which you need to add onto chemotherapy,” he said.
Dr Ibrahim said that while stage 4 patients do respond to chemotherapy, the problem is that the cancer tends to return quite quickly and second-line chemotherapy has poor results.
“So you need better and newer agents to salvage these patients, and some of the newer drugs like ramucimurab, we can use to enhance or improve the survival of some of these patients.”
“But we’re still a long way away from having good effective control, compared to say lung cancer.
“Previously, the survival rate for stage 4 lung cancer was only three to six months.
“Today, they survive more than one to two years.”
And this is due to the discovery of “druggable targets” where molecular studies have identified pathways that can be blocked by certain drugs to prevent the tumour from growing.
“We may not be able to cure them, but certainly, if we can improve their survival with good quality of life, I think that is the first step we need to do,” said Dr Ibrahim.