[In-depth Science] National Liver Care Day | Stay away from liver cancer and take care of your liver

On February 3, 2021, musician Zhao Yingjun died of liver cancer at the age of 43; on February 27, 2021, comedy star Wu Mengda died at the age of 68, also due to liver cancer, and it was heartbreaking that "Uncle Da" only had 3 months from the time he was diagnosed with liver cancer to his death.

It is thought-provoking that my country is a country with a high incidence of liver cancer. Let us first understand liver cancer through several sets of data: According to the latest global cancer burden data released by the World Health Organization's International Agency for Research on Cancer in December 2020, the number of people with primary liver cancer in my country accounted for 42.5% of the world's total in the past five years, with an average annual incidence of 995,000 cases, mostly male patients. In my country, 92.5% of liver cancer patients have chronic hepatitis B virus infection.

In 2020, liver cancer ranked high in my country in two indicators: the incidence rate ranked fifth among malignant tumors, and the mortality rate ranked second, with about 391,000 deaths. The above data show the severity of liver cancer. So what is liver cancer? What are the symptoms of liver cancer? How is liver cancer caused? How to detect liver cancer early? What are the carcinogenic factors in life? How to prevent liver cancer?

March 18th is National Liver Health Day. We specially invited Dr. Fan Chunlei, chief physician of the Liver Disease and Digestive Center of Beijing You'an Hospital affiliated to Capital Medical University, to answer some questions about liver cancer. Let us learn about liver cancer and protect our precious "liver" together.

1. What is liver cancer?

Before explaining liver cancer, let's first learn about the liver. The liver is located deep inside the ribs on the right side of the body and is one of the important digestive organs of the human body. The liver has very powerful functions. It is equivalent to the body's metabolic factory, participating in the synthesis, transformation and decomposition of various nutrients, such as protein, fat, sugar and vitamins; participating in the metabolism of hormones in the body, as well as the decomposition and detoxification of alcohol, drugs and metabolic waste; in addition, it can secrete bile to help digestion, produce coagulation factors to help stop bleeding, etc.

Liver cancer is the abbreviation of primary liver cancer, which refers to malignant tumors occurring in liver cells or intrahepatic bile duct cells, which can seriously affect various functions of the liver.

2. What causes liver cancer?

The cause of liver cancer is the result of multiple factors, including internal and external factors. The internal factors mainly refer to genetic background and genetic susceptibility. People with a history of liver cancer in their family, especially in their immediate family members, are more likely to develop liver cancer. External factors are mainly environmental factors, including viruses, alcohol, drugs, poisons, autoimmune attacks, etc. The occurrence of liver cancer often goes through the "trilogy", namely "hepatitis - cirrhosis - liver cancer". So what are the common causes of liver cancer?

1. Viral hepatitis

Long-term chronic infection of viral hepatitis is the most important of the multiple pathogenic factors of liver cancer. Common ones include chronic hepatitis B (HBV) and chronic hepatitis C (HCV), of which the former is the most common. As mentioned above, 92.5% of liver cancer patients in my country have chronic hepatitis B.

The long-term presence of large amounts of viruses will continue to attack liver cells, causing repeated inflammation of liver cells until they become necrotic. Our body's cells have a self-repair mechanism, and scars will appear when wounds heal, and liver cells are no exception. In the process of repeated damage and repair of liver cells, it is easy for "scars" that have no function and damage the internal structure of the liver to appear. We call this liver fibrosis. Fibrotic liver tissue is not as "elastic" as normal tissue. It will gradually form nodules, causing the liver to gradually harden. Over time, it will form the protagonist we are going to talk about next: cirrhosis. In addition, the continued presence of the virus can cause liver cells to become malignant. There is a misunderstanding here. Some people believe that liver cancer will not occur if liver function is normal. In fact, the viral load in the human body is directly related to the occurrence of liver cancer.

2. Cirrhosis

About 70% of liver cancers are formed on the basis of cirrhosis, and about 25% of patients with cirrhosis can develop into liver cancer. As normal liver tissue undergoes a cycle of inflammation, necrosis, repair, and fibrous tissue filling, cirrhosis forms and can further develop into liver cancer. The most common causes of cirrhosis are chronic hepatitis B and chronic hepatitis C; in addition, alcoholic liver disease, non-alcoholic fatty liver disease, primary cholestasis, and hemochromatosis can also cause cirrhosis and then liver cancer.

3. Alcoholic liver disease

From the liver function introduced above, we know that the alcohol ingested into the body needs to be metabolized in the liver. Alcohol itself is very harmful to liver cells, especially long-term heavy drinking, which can seriously damage liver cells and their functions. Alcohol can directly promote liver cell cancer; long-term heavy drinking, such as drinking more than 50-70 grams a day, can also induce cirrhosis and lead to liver cancer. This really sounded the alarm for "alcohol lovers".

4. Nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease refers to a type of liver disease caused by excessive fat deposition in liver cells, in addition to alcohol and other factors that clearly damage the liver. This cause is becoming an important cause of liver cancer, which can directly lead to liver cancer without going through cirrhosis.

Such patients often have abnormal glucose and lipid metabolism, such as insulin resistance, which can be simply understood as abnormal blood sugar lowering function; or abnormal lipid metabolism, manifested as obesity, etc. When they have diabetes, the risk of liver cancer is 1.8-2.5 times higher than that of normal people.

5. Family history and genetic factors

Family history is an important risk factor for liver cancer. For example, if a close relative, such as a parent, sibling, etc., has liver cancer, then the risk of liver cancer will increase significantly. During childbirth, the mother may transmit the hepatitis B virus or hepatitis C virus to the child, and long-term close contact can also spread hepatitis B. If it is not discovered and treated in time, chronic hepatitis will gradually develop, leading to cirrhosis and liver cancer.

In addition, genetic factors, such as carrying genes that are likely to induce liver cancer, will significantly increase the risk of developing liver cancer in the future.

6. Other risk factors

Long-term exposure to aflatoxin B1 may induce liver cancer, and can also directly lead to liver cancer without going through the cirrhosis stage. The International Agency for Research on Cancer classified it as a Class I carcinogen as early as 1987. It is mainly found in moldy grain and oil products, nuts and other foods. When long-term exposure to aflatoxin B1 and chronic hepatitis B are present, the risk of liver cancer increases by about 60 times.

In addition, some unhealthy lifestyles, such as smoking, drinking, obesity, drinking contaminated water, and long-term exposure to nitrosamines, organochlorine pesticides, and other carcinogenic chemicals, will also increase the risk of liver cancer.

3. What are the symptoms of liver cancer?

So what are the symptoms after liver cancer occurs?

In fact, there are no obvious symptoms in the early stages of liver cancer. By the time typical symptoms appear, it has usually developed to the middle or late stages. One of the reasons why "Uncle Da" died in just three months from the discovery of liver cancer may be based on this. As the disease progresses, the patient will gradually develop the following symptoms:

1. Pain in the liver area

There are abundant nerve endings distributed on the surface of the liver and peritoneum. As the disease progresses, the rapidly growing tumors will pull the capsule covering the surface of the liver, or compress the surrounding organs, invading the peritoneum and causing liver pain, that is, pain felt deep in the ribs on the right side of the body. This is usually the first symptom of liver cancer, which is often manifested as persistent or intermittent dull pain, dull pain or distending pain, and will gradually worsen as the disease progresses.

When the tumor is located on the right side of the liver, it manifests as pain in the right rib angle; when the tumor is located in the left lobe of the liver, it usually manifests as upper abdominal pain, which many people mistakenly believe to be a stomach disease; when the tumor ruptures and bleeds, severe abdominal pain may occur, which is unbearable and may even lead to shock due to the large amount of bleeding.

However, there are no pain nerves inside the liver. If the cancer is inside the liver, or grows slowly and does not touch the surface of the liver or the peritoneum, the patient will not feel pain either. This gives liver cancer an opportunity to develop "silently."

2. Digestive tract symptoms

As the tumor grows larger, it will compress the surrounding gastrointestinal tract, causing gastrointestinal congestion, while also damaging liver function and causing a series of digestive tract symptoms, such as loss of appetite, nausea, vomiting, abdominal distension, diarrhea, and so on.

3. Bleeding tendency and bleeding

Because the liver is an organ that produces coagulation factors, which are essential for the body to stop bleeding, when liver cancer damages liver function and causes insufficient coagulation factors, the patient will have a tendency to bleed, manifested as bleeding gums, skin ecchymoses, etc. Esophageal varices caused by liver cirrhosis will cause gastrointestinal bleeding after rupture, manifested as vomiting blood, black stools, etc.

4. Systemic manifestations

In the late stage, patients will have fever, which is usually a persistent low-grade fever, and antibiotics are ineffective; they will experience general fatigue and weight loss, and the condition will gradually worsen; they will also suffer from malnutrition and cachexia, manifested as extreme weight loss, which is not an exaggeration to describe as emaciated, anemia, complete bed rest, inability to take care of themselves, etc., causing extreme pain to patients.

5. Paraneoplastic syndrome

Paraneoplastic syndrome refers to a syndrome that appears at the same time as liver cancer symptoms or before liver cancer symptoms. It is caused by certain substances produced by the liver cancer itself. It mainly includes spontaneous hypoglycemia, polycythemia, hypercalcemia, hyperlipidemia, thrombocytosis, etc.

In addition to the above symptoms, patients with mid-to-late stage liver cancer also have some physical signs, such as jaundice, hepatomegaly, splenomegaly, ascites, etc. We can see that patients with mid-to-late stage liver cancer will have a very large abdomen.

4. How to detect liver cancer early

We have mentioned before that the mortality rate of liver cancer is very high, and the main reason is that it is not discovered in time. The reason why liver cancer is not discovered in time is that there are no obvious symptoms in the early stage, which is not enough to attract everyone's attention.

The liver is a powerful organ with a strong regenerative capacity. When it is damaged, it will first repair itself. As long as the liver has about 30% of its normal function, it is enough to meet the daily needs of the human body, so there may be no symptoms in the early stages.

In addition, some people call the liver a "silent organ" or "dumb organ" because it is insensitive to pain, so patients with early liver cancer may not feel pain at all, and when they feel pain, it is already in the middle or late stage. Therefore, early detection, early diagnosis, and early treatment are the key links to improve the survival rate of liver cancer patients, especially those at high risk of liver cancer, who should race against time to gain precious time for treatment.

Is there a way to detect liver cancer early? The answer is yes. There are two main ways to detect liver cancer early: be alert to related clinical symptoms and early screening.

1. Be alert to relevant clinical symptoms

For patients with chronic liver disease, especially males aged ≥40 years and females aged ≥50 years, if they find pain in the liver area, that is, pain and discomfort in the right upper abdomen, or symptoms such as abdominal distension and loss of appetite, do not mistakenly think that it is just gastrointestinal discomfort. It is recommended to seek medical attention in time to avoid delaying the condition.

2. Early screening

Early screening is to regularly use various examination methods to check whether there are any lesions in the liver. It is divided into routine screening and enhanced screening.

(1) Routine screening

① Liver ultrasound: can show tumors with a diameter of more than 2 cm. Liver ultrasound can not only show the size of the tumor, but also what the tumor looks like, where it grows, and what relationship it has with surrounding blood vessels, etc. It is often combined with AFP examination to determine whether there is early liver cancer.

②AFP test: AFP is alpha-fetoprotein, which is a tumor marker for liver cancer. When a blood test finds that this tumor marker is abnormally elevated, combined with abnormal changes in ultrasound or other imaging tests, it helps diagnose early liver cancer. However, simply doing an AFP test is not very meaningful, because when the liver is damaged due to other reasons, AFP may also increase. Therefore, if you find that AFP is elevated during the test, you don't need to be too nervous.

(2) Strengthening screening

① CT: CT has a much higher resolution than ultrasound, and its imaging is clearer, allowing for a comprehensive understanding of the tumor, such as size, number, location, shape, border, relationship with the intrahepatic duct, whether there is thrombus in the surrounding veins, whether it has invaded other adjacent organs, etc. It can also see relatively small tumors that are invisible to ultrasound. Therefore, when routine screening finds suspicious abnormalities, further CT examinations are required.

② Magnetic resonance imaging: MRI, which has better resolution and imaging effect than CT, can observe the internal structure and necrosis of the tumor, has a higher probability of detecting small liver cancer and liver cancer, and has no radiation. Therefore, it is often used as one of the important means of early screening for liver cancer.

With early screening methods, not everyone, at every age, and every year needs to do it. According to the risk level of liver cancer in patients with chronic liver disease, there are 4 risk stratifications, and the frequency and items of screening in each risk stratification are different. They are:

1. Low-risk groups

That is, the early and stable stages of chronic liver disease, including chronic hepatitis B carrier status, simple fatty liver and benign inherited metabolic liver disease. This group of people only needs to undergo routine screening (liver ultrasound and serum AFP) once a year.

2. Moderate-risk group

That is, people aged ≥30 years and whose chronic liver disease is in the active stage. For example, patients with chronic hepatitis B and chronic hepatitis C, whose condition is unstable, whose ultrasound examination shows inflammation, and whose viral DNA test is positive, etc. It is recommended that this group of people undergo routine screening every 6 months.

3. High-risk groups

Anyone with any of the following is considered a high-risk group:

(1) Patients with chronic hepatitis B, chronic hepatitis C, alcoholic fatty liver disease, non-alcoholic fatty liver disease, autoimmune liver disease, drug-induced liver injury, and Wilson's disease.

(2) Males aged ≥40 years and females aged ≥50 years who suffer from chronic hepatitis B or chronic hepatitis C.

(3) People aged 30 years and above with chronic hepatitis B and a family history of liver cancer; or chronic hepatitis B patients who are long-term smokers, alcoholics, obese, have a clear history of exposure to carcinogens, or have diabetes.

High-risk groups are more likely to develop liver cancer, so routine screening is recommended every 3-6 months and enhanced screening (MRI or CT) every 6-12 months.

4. Extremely high-risk groups

The above high-risk groups are extremely high-risk groups if they have one or more of the following:

(1) Patients with liver cirrhosis caused by various reasons.

(1) Ultrasound, CT and other imaging examinations reveal nodules in the liver or abnormal blood perfusion, but these are not typical manifestations of liver cancer.

(2) When doing laboratory tests, pay attention to the test results. If the results show that serum alpha-fetoprotein AFP ≥ 20ng/ml, with or without abnormal prothrombin DCP ≥ 40mAU/ml and/or AFP-L3 ≥ 15%, it also means that the patient is in the extremely high-risk group.

(3) People who have been confirmed to have abnormal hyperplastic nodules in the liver during imaging examinations or pathological examinations of liver tissue.

The extremely high-risk group is prone to developing liver cancer, so this group of people needs to undergo routine screening every 3 months, including liver function, alpha-fetoprotein, alpha-fetoprotein isomers, abnormal prothrombin, B-ultrasound and other imaging examinations. Enhanced screening with enhanced CT or enhanced MRI can be performed when necessary.

5. What are the risk factors for liver cancer in life?

1. Aflatoxin B1

In fact, aflatoxin B1 is not unfamiliar to everyone. Many elderly people pay attention to thriftiness and are reluctant to throw away even moldy food. Aflatoxin B1 exists in moldy food or objects. Aflatoxin is a metabolite produced by fungi such as Aspergillus flavus and Aspergillus parasiticus. These molds like to live in spoiled grain and oil products, nuts and other foods rich in fatty acids, and like dark and humid environments. Let's take an example:

(1) Spoiled food: such as rice, corn, peanuts, especially cooked rice and corn, which are prone to spoilage and mold when left for too long, and produce aflatoxin B1.

(2) Poor quality edible oils and sauces: For example, peanut oil and corn oil made at home or in small workshops are prone to the presence of aflatoxin due to the lack of strict hygiene conditions and the process of removing toxic and harmful substances, or accidentally pressing moldy peanuts and corn into oil. In addition, peanut butter and sesame paste that have been stored for a long time or are of poor quality are also prone to the growth of aflatoxin.

(3) Spoiled nuts: For example, bitter melon seeds and walnuts often have a large amount of aflatoxin on the skin.

(4) Black fungus that has been soaked in water for too long: Black fungus itself does not contain aflatoxin, but if it is soaked in water for too long, it will easily deteriorate and breed mold.

(5) Unwashed chopsticks and chopping boards: Wooden chopsticks and chopping boards are prone to retaining debris from peanuts, corn, etc. If they are not cleaned in time and are placed in a humid environment, they will also breed aflatoxin.

(6) Contaminated drinking water: Drinking water may be contaminated by Aspergillus flavus.

If you are in contact with moldy food or water for a long time, it will exceed the liver's detoxification and metabolic capacity, causing aflatoxin to accumulate in the liver, which may induce liver cancer over time.

2. Alcoholism

This lifestyle is an accomplice in inducing many types of cancer and poses a serious threat to human health. Alcohol can directly damage liver cells, so alcoholics are at a higher risk of liver cancer than others. If a chronic hepatitis B or chronic hepatitis C patient drinks alcohol, his risk of liver cancer is dozens of times higher than that of others. Data show that among liver cancer patients, about 15% are related to drinking.

3. Staying up late for a long time

As people age, especially men aged 40 or above and women aged 50 or above, their immunity will gradually decline. Coupled with staying up late for a long time, liver cells cannot get rest, which will affect their repair, metabolism, detoxification and other functions, and over time will increase the risk of cancer.

4. Obesity

Nowadays, with the development of Internet technology, many people tend to stay at home, do not exercise, and prefer a high-oil and high-fat diet. As a result, the body consumes excess calories, which will form fat accumulation in the body, causing obesity and easily leading to a series of metabolic problems, which is not good for the liver. Data show that patients with chronic hepatitis B and chronic hepatitis C, if accompanied by obesity and diabetes, have a 100-fold increase in the risk of liver cancer.

6. How to prevent liver cancer?

Although the incidence and mortality rates of liver cancer in my country are high, we have learned about the causes and risk factors of liver cancer. As long as we pay attention to them in our daily lives, we can prevent the occurrence of liver cancer to the greatest extent.

1. Vaccination

Chronic hepatitis B is the most common cause of liver cancer, and vaccination with hepatitis B vaccine can effectively prevent hepatitis B, thereby greatly reducing the risk of liver cancer.

2. Improve unhealthy lifestyle

(1) Stay away from aflatoxin: reduce the amount of food stored, shorten the storage time of food, keep the storage environment dry, and prevent food from getting moldy; decisively throw away spoiled or moldy rice and corn, and peanut butter, sesame paste, nuts, etc. that have changed their taste or become bitter; do not make or buy inferior peanut oil or corn oil at home; eat black fungus promptly after it has been soaked; be sure to thoroughly wash chopsticks and cutting boards, and dry them promptly; and replace drinking water promptly if there is any problem with it.

(2) Quit drinking; avoid staying up late for long periods of time, and make sure to balance work and rest.

(3) Control your diet, exercise, and promote a healthy diet, such as low-salt, low-fat, a combination of meat and vegetables, and increased intake of fruits and vegetables; at the same time, strengthen physical exercise and actively control weight.

(4) Avoid long-term exposure to toxic and harmful chemicals and do not abuse drugs.

3. Antiviral treatment

If you already have hepatitis B or hepatitis C, you need to seek medical attention immediately. Chronic hepatitis B patients often need to take antiviral drugs for a long time, while chronic hepatitis C patients can completely eradicate the virus by taking antiviral drugs for 3 months (even so, regular screening is still required). This can greatly reduce the risk of liver cancer.

4. Actively treat other chronic liver diseases

Actively treating alcoholic liver disease, non-alcoholic fatty liver disease, and cirrhosis caused by various reasons can also play an effective role in preventing liver cancer.