The gallbladder is an apple-sized organ near the liver and is primarily responsible for storing bile, a substance produced by the liver and used by the body to break down the fats we eat.

Thousands of years ago, humans might have eaten one big meal every few days and “we might have needed that extra boost of bile to help us digest it, if the liver couldn’t produce it fast enough,” says Dr Anita Balakrishnan, a consultant hepatopancreatobiliary (HPB) surgeon at Britain’s Addenbrooke’s Hospital and an associate lecturer at the University of Cambridge.

“The gallbladder is a vestigial organ, like the appendix – now we don’t really need it for normal digestion, and sometimes it causes trouble.’”

Cancer occurs when healthy cells in the gallbladder develop genetic mutations that cause them to grow and multiply out of control. Just over 1000 cases have been diagnosed in Britain each year, equivalent to about three a day, and, “sadly, it’s an aggressive cancer,” says Balakrishnan.

What are the risk factors?

According to Cancer Research UK, women account for 71% of cases. In women who have given birth, particularly those who have had five or more children, the risk is increased.

The reason for this is not fully known, but women are two to three times more likely to suffer from gallstones, which are a major risk factor for gallbladder cancer. Oestrogen can increase cholesterol levels in bile and decrease gallbladder contractions, which can lead crystals to form in the bile and create stones. During pregnancy, the gallbladder also grows in volume.

“Having gallstones doesn’t necessarily mean you’ll get cancer, but they cause inflammation of the gallbladder, which puts people at a higher risk,” says Shahid Farid, a consultant surgeon with a specialism in gallbladder surgery at Nuffield Health Leeds Hospital.

People with a family history of gallbladder cancer are five times more likely to develop the disease, and it is more common in people of Asian descent.

Smoking and obesity also increase the risk, with the rise in obesity since the mid-1990s believed to be a major factor in the increase in cancer among younger people, in particular.

What are the main symptoms, treatment and survival rate?

Unfortunately, gallbladder cancer is often a silent disease which becomes symptomatic only in its later stages.

“Any symptoms people have are usually non-specific, such as tiredness and perhaps some abdominal discomfort,” says Farid.

Eventually, symptoms can include jaundice, pain in the upper right abdomen, weight loss, nausea and vomiting. “By that stage, it has usually grown beyond the gallbladder and is at an advanced stage,” he says.

It is often detected by chance during operations, for instance to remove gallstones, and if it is contained within the gallbladder, the five-year survival rate is 60-70%. If it has spread to local tissues or lymph nodes, survival rates are almost 30%, while if it has spread to more distant areas, rates are under 5%.

If possible, treatment involves surgery, along with chemotherapy.

What can we do to minimise our risk?

1. Maintain a healthy weight

Being overweight and obese is the second biggest cause of cancer in Britain, after smoking. Several studies have found a link between an increased risk of gallbladder cancer and a BMI (body mass index) of over 25, with the World Cancer Research Fund saying the risk increases by 25% for every 5kg per square metre increase in BMI.

One recent Norwegian study found a concerning 47% increased risk in women per 5kg/m2 increase in BMI, while the increased risk in men was smaller and not statistically significant. It also showed a decreased survival rate for overweight and obese women with gallbladder cancer.

“Eating a healthy diet and staying within a healthy BMI range will help avoid gallbladder cancer,” says Dr Balakrishnan. “Giving up smoking and keeping alcohol consumption under recommended limits is also vital.”

2. Look after your microbiome

In recent years, scientists have increasingly focused on the microbiome, the ecosystem of bacteria which populates the gut, when searching for causes of the increase in early-onset cancers.

“Research into the influence of the microbiome on cancers including gallbladder cancer is still in its early days, but it’s only logical that it plays a part,” says Farid. “Our microbiome can contribute to inflammation, and that can predispose us to cancer.”

A Chinese study from 2023 investigated the microbiome of patients with biliary tract cancers, of which gallbladder cancer is one. It found patients with the disease had increased levels of the Enterobacteriacae bacteria, and decreased levels of others including Clostridia, suggesting an imbalance. Both are associated with inflammation.

We can boost the diversity and good bacteria in our microbiome with fermented foods such as kefir, sauerkraut and kimchi, and prebiotic foods like mushrooms, onions, garlic, asparagus, leeks and apples, which feed the bacteria in our gut.

Good bacteria such as Clostridia can naturally be found in food such as vegetables, while high-fibre foods such as fruit, wholegrains and nuts will also nurture the microbiome.

3. Avoid fried, fatty foods and sugary drinks

The link between different types of diet and higher rates of gallbladder cancer is still being researched, but some studies have highlighted certain principles by which it’s best to live.

Eating too many fatty and fried foods has been linked to an increased chance of getting the disease because they raise cholesterol which is linked to gallstones, which are in turn strongly linked to gallbladder cancer.

Red meat, and particularly processed meat containing nitrates, is also associated with a higher risk, so cutting down to 455g of cooked lean red meat per week is recommended.

Drinking sugar-sweetened and artificially sweetened beverages has been shown to double the risk of gallbladder cancer when individuals drank 400ml or more per day. This is thought to be because increased sugar consumption is linked to a higher BMI, and also to Type 2 diabetes, which increases the risk of cancer.

Ultra-processed foods (UPFs) are linked to a higher incidence of all cancers, and researchers believe they may be a major driver of the increase in cancers among people aged under 50. “Reducing the amount you consume and eating unprocessed food where possible is best,” says Farid.

4. Eat the DASH diet

One Swedish study revealed that two types of healthy diet are associated with a lower risk. One is the Dietary Approach to Stop Hypertension, or Dash, which includes fruits, vegetables, whole grains, low-fat dairy, and lean protein from chicken, fish, beans and nuts. It avoids foods high in salt, saturated fat, and added sugar. The second is the Mediterranean diet, which follows very similar principles.

One Indian study reported that eating sweet potatoes was associated with a lower risk of gallbladder cancer, along with green chillis, radish, mango, orange and melon – all of which contain high levels of antioxidants.

5. Exercise regularly

Regular physical activity has been shown to be likely to reduce the risk of gallbladder cancer, and studies have shown it can increase the diversity of the gut microbiome.

“Exercise also promotes cell turnover in a different way to when you’re sedentary,” says Farid. “It also reduces the amount of fat and also inflammatory cytokines in your blood. So it’s one of the most important things you can do to modify your risk of many cancers, including gallbladder.”