In view of the increasing incidence of colorectal cancer in China in recent years and the fact that the cure rate has not improved significantly, we think it is very necessary to carry out the popularization of knowledge about the prevention and treatment of colorectal cancer. Now, we list the related knowledge here, hoping that we can master the prevention knowledge of this disease, and make good efforts to prevent and treat colorectal cancer together with doctors, so as to make some contribution to improve the health quality of all people.
1.Why are there more and more patients suffering from colorectal cancer? What is the reason for this?
Here are two sets of information: one is the comparison of 20-year colorectal incidence rate in five provinces and cities, and the other is the comparison of census figures in recent decades (plus two slides). From these two figures, we can show that there is indeed a significant trend of increasing the number of colorectal cancer cases in China. Based on the findings of experts in various countries, most people believe that long years of high-protein, high-fat and low-fiber dietary habits are conducive to the development of colorectal. Of course, it is not true that long years of high-protein, high-fat and low-fiber diets will lead to colorectal cancer. Other related factors, such as years of ulcerative colitis, multiple people in the family suffering from colorectal cancer or polyposis, gallbladder removal for more than 10-20 years, lower abdominal radiation treatment, chronic schistosomiasis infection, etc. are also related to the development of colorectal cancer.
2.Some people say “the better you eat, the more likely you are to get colorectal cancer”. Is this statement correct?
The incidence of colorectal cancer in different regions and countries around the world can vary by more than 10 times. Economically developed regions and countries, such as North America, Western Europe, Australia and New Zealand, the incidence of colorectal cancer are more than 25-35/100,000, in the past 20 years, Japan, which was originally a high incidence of stomach cancer, with its rapid economic development, the increase in the incidence of colorectal cancer has exceeded that of stomach cancer, according to statistics, from 1969 to 1981, the mortality rate of colorectal cancer in Japan increased by 44% for men and 40 percent. In contrast, the incidence rate in India is only 1-3/100,000, and the incidence rate of colorectal cancer in some African countries is even less than 1/100,000. The statistics of China in the past 30 years show that the prevalence of colorectal cancer has increased from <10/100,000 in the 1960s to more than 20/100,000 in the 1980s, and the mortality rate of colorectal cancer in Shanghai increased by 75% from 1972 to 1989.
According to our census data of more than a dozen towns in the northern region of China, the incidence of colorectal cancer is significantly higher in cities, especially in large cities, than in small towns and rural areas. In the cities, the incidence rate of people with less physical activity is higher than those with more physical activity. From the results of etiological studies on colorectal cancer in various countries, high-fat and high-protein diet, reduced exercise, environmental pollution and bad habits are all related to the development of colorectal cancer, and the above-mentioned social conditions are related to economic development, according to which, some people believe that the better you eat, the more likely you are to get colorectal cancer. In fact, colorectal cancer, like other cancers, is the result of the interaction between environmental and genetic factors. In terms of diet itself, high-fat, high-protein and low-fiber diet structure may play a role in promoting colorectal cancer.
Since a high-fat, high-protein and low-fiber (coarse grains, vegetables and fruits are high-fiber foods) diet is likely to cause colorectal cancer, what kind of recipes are “healthy recipes”?
Recently, the USDA recommended a “pyramid” food structure, which they believe is good for colorectal cancer prevention. The bottom of the tower consists of various grains, pasta and rice, the middle of the tower is vegetables and fruits, the top of the tower is meat, poultry, aquatic products, eggs, beans and dairy products, and the tip of the tower is high-fat foods. In fact, this food structure is exactly the daily recipe in Asia, especially in China. From the perspective of colorectal cancer prevention, maintaining our traditional diet structure is a “healthy recipe”.
The European Cancer Prevention Organization and the International Union of Nutritional Sciences have also made the following recommendations.
(1) Reduce the intake of fatty foods (including animal oil and vegetable oil), replace meat with fish, poultry, lean meat and low-fat dairy products with excessive animal oil, and replace fried foods with boiled and steamed foods.
(2) Increase the intake of green leafy and root vegetables and fruits.
(3) Eat more starchy and fiber-rich foods.
(4) Maintain an appropriate body weight.
(5) Salt intake should be less than 5 grams per day.
(6) Eat more fresh food, less pickled and smoked food, no moldy food.
Drink less alcoholic beverages.
4.Will constipated people be prone to colon cancer?
Constipation refers to too little stool or difficult defecation, dry stool and other manifestations. Generally speaking, if you have a bowel movement once every 2-3 days, it cannot be called constipation. Our stool contains a carcinogenic substance called “secondary bile acid”, which comes from the bile secreted by the liver. When we eat, especially when we eat oily food, the gallbladder contracts and expels the stored bile to aid digestion. The bacteria in the intestinal cavity break down the bile entering the intestinal cavity into “secondary bile acids”, which reside in the feces.
From this perspective, constipation is conducive to the occurrence of colorectal cancer. Of course, in addition to “secondary bile acids”, there are also many digested food residues and bacteria in the feces. Toxins produced by bacteria and toxic products of bacterial enzymes remain in the intestinal lumen for a long time due to constipation, and the irritation of the intestinal mucosa and the absorption of some water-soluble substances have adverse effects on the human body. Although it cannot be said that constipation can induce colorectal cancer, it can be said that constipation plays a role in the occurrence of colorectal cancer. For this reason, it is meaningful to develop the habit of regular bowel movement and prevent constipation in the prevention of colorectal cancer.
5.Will patients who have undergone gallbladder removal surgery be prone to colorectal cancer?
The gallbladder is like a reservoir for storing bile, where most of the bile secreted by the liver is stored. After we eat, especially after we eat food containing a lot of fats and oils, the gallbladder contracts and discharges the stored bile into the intestine to help digestion and absorption. If the gallbladder is removed, there is no place to store the bile produced by the liver, so the bile is continuously discharged into the intestine.
As mentioned above, the bile entering the intestine is decomposed by the bacteria in the intestine to produce carcinogenic “secondary bile acids”, which are carcinogens that act on the intestinal mucosa for years and may cause cancerous changes in the stimulated intestinal mucosa. According to many western research data, this process of becoming cancerous takes about 10-15 years or more. However, there are some researchers who are against it, they observed thousands of patients who had gallbladder removal and those who did not have such surgery, and found that the chance of colorectal cancer is similar in these two types of people. Therefore, so far, it cannot be said with certainty that patients who have undergone cholecystectomy are more likely to get colorectal cancer.
6. Can chronic colitis evolve into colorectal cancer?
People usually refer to long-term diarrhea and abdominal pain as chronic colitis. In fact, chronic abdominal pain and diarrhea are not always “chronic colitis”, and even the “chronic colitis” diagnosed by doctors is not always related to colorectal cancer. A kind of chronic colitis that is really related to colorectal cancer is medically called “ulcerative colitis”. The main symptoms of this disease are abdominal pain, diarrhea, blood or pus in the stool, and fever in severe cases. Once the disease is present, it is often prolonged and does not heal. Colonoscopy can reveal extensive ulcers and inflammation in the large intestine. Most of these patients can recover after regular treatment by doctors. Very few patients with ulcerative colitis who have been in serious condition for many years have more chances of developing colorectal cancer than normal people. According to the statistics, the following two factors are more closely related to cancer.
The greater the extent of the lesion, the higher the risk of cancer (after 20 years of illness, the chance of cancer in patients with total colitis is twice as high as in patients with left hemicolectasis, and the average age of cancer is 5-10 years earlier than the latter); the longer the duration of ulcerative colitis, the greater the chance of cancer, the chance of cancer in the first 8 years of illness is only 1% or less, after that, the chance of cancer increases by 0.5-1% every year, and the chance of cancer in more than 20 years The chance of cancer can be 5-10%.
7.Can radiation treatment (commonly known as baking electricity) cause rectal cancer?
Many studies have shown that the chance of rectal cancer increases significantly after radiation treatment for tumors of female reproductive organs (ovaries, uterus). Therefore, women with a history of lower abdominal radiation therapy (electrocautery) should be vigilant and undergo colonoscopy as soon as rectal symptoms (blood in the stool, cramping, change in bowel habits, etc.) appear.
Radiation-induced rectal cancer does not run in families, unlike another type of medical condition called “hereditary non-polyposis colon cancer”, which has prominent genetic characteristics. This type of patient has colorectal cancer and may or may not have female genital tumors at the same time. Since this kind of tumor has the characteristic of family gathering, not only the patient himself should be treated, but also his relatives should be examined and treated (to be discussed later).
8.Is colorectal cancer hereditary?
Scientific research proves that most human diseases are influenced by genetic factors. Except for trauma, almost all diseases are influenced by both environmental and genetic factors, only that some diseases are more influenced by environmental factors, while others are more prominently influenced by genetic factors. Colorectal cancer is no exception. If a person has a relative with colorectal cancer, he will have more chances to develop colorectal cancer under certain conditions, such as eating high protein, high fat and less fiber (fine rice, fine grain) food for a long time. Of course, the occurrence of colorectal cancer is not simply 1+1=2 (heredity + high-fat diet = colorectal cancer), but a multifactorial, multi-step process of accumulation of cancer-causing factors over a long period of time.
Internal factors are the basis of change, and external factors are the conditions of change. Lack of genetic background of colorectal cancer is not easy to get colorectal cancer even if you are subjected to the effect of carcinogenic factors. On the contrary, if you have a family history of colorectal cancer, you will easily get colorectal cancer under the effect of certain cancer-causing factors. Therefore, if a relative, especially an immediate family member, has a patient with colorectal cancer, each member of the family should be examined regularly. If necessary, treatment should be carried out to prevent the occurrence of colorectal cancer.
9.Why are some colorectal cancers easy to be inherited and those colorectal cancers easy to be inherited?
As mentioned above, it should be said that all colorectal cancers are affected by genetic factors, but their hereditary strengths are different. There are two kinds of colorectal cancer hereditary strength: the first is known as “familial adenomatous polyposis”, and the second is called “hereditary non-polyposis colorectal cancer”. These two types of colorectal tumors account for only a very small percentage of all colorectal cancers.
In the former, the average age of onset is only 20 years old, and there can be hundreds of adenomas (benign tumors growing from the intestinal mucosa) in the large intestine, and 10 years after the appearance of these benign tumors, some of them start to become cancerous. People with this disease can also have bone tumors, skin tumors and brain tumors at the same time. Once the disease is detected, the patient and his or her immediate family need to be followed up for a long time and have the necessary tests.
The latter (hereditary non-polyposis colorectal cancer) develops 15-20 years earlier than the average colorectal cancer. The cancer mostly occurs in the right half of the colon, and sometimes there are several cancers in the colon at the same time (called multiple primary cancers), which can easily recur after surgery. Other cancers, such as uterine cancer, ovarian cancer, breast cancer, pancreatic cancer, lung cancer, etc., often appear in his family, so some people call it “cancer family syndrome”.
Once this tumor appears in the family, all the immediate family members of the patient should go to the hospital for examination to achieve the purpose of early detection, early diagnosis and early treatment.
10.Will all colon “polyps” become cancerous?
First of all, we need to clarify what is a “polyp”. The so-called “polyps” refer to various bulges in the intestine (mucosal surface). Medically speaking, there are two types of polyps: tumor and non-tumor. The former type is called “adenoma”, which is a true benign tumor. The latter type of polyps are not tumors, including inflammatory polyps and hyperplastic polyps, which are not related to the occurrence of cancer.
So, do all adenomas become cancerous intensities? Actually, not all adenomas will become cancer. The most likely to become cancerous is the aforementioned “familial adenomatous polyposis”, which can have abdominal pain, diarrhea, blood in stool, or no symptoms until cancer is detected. It has been observed that this disease occurs around the age of 20, develops symptoms around the age of 33, becomes cancerous around the age of 39, and dies at an average age of 42. It has been found that 80% of these patients have “congenital retinal pigment epithelial hyperplasia” as a sign that the suspect can detect the disease through an eye examination (fundoscopy). Since the disease is familial, if one member of the family is diagnosed, the others should be examined (including fundoscopy). Some of these “adenomas” are associated with skin, muscle, bone, or brain tumors, some with dark spots on the skin and mucous membranes (hyperpigmentation of the palms of the hands and lips), and some with nail atrophy, hair loss, and dark spots on the skin. Since polyps grow in the intestine, they cannot be diagnosed without special examination, but the above-mentioned characteristic signs can alert us to go to the doctor.
With the exception of the above mentioned “familial adenomatous polyposis”, most “adenomas” are not obviously hereditary. There is a correlation between the size of this adenoma and the cancer, and there are 4570 adenomas. The rate is 12.4%. It can be seen that the larger the tumor, the greater the chance of becoming cancerous. In addition, if the adenoma is found to be “villous adenoma” by microscopic examination, it has a high chance of becoming cancerous (about 40%), while if it is “tubular adenoma”, it has a low chance of becoming cancerous (less than 5%). Non-neoplastic polyps, especially small polyps less than 0.5cm in diameter, will almost never become cancerous.
11.Is there any relationship between schistosomiasis and colorectal cancer?
It has been found that the incidence of colorectal cancer is higher in schistosomiasis endemic areas, thus it is believed that schistosome eggs are deposited in the intestinal mucosa and cause mucosal carcinoma there through mechanical or chemical stimulation. Others have found early signs of cancer in the intestinal mucosa at the site of schistosome egg deposition. Based on these findings, some people believe that intestinal schistosomiasis can cause colorectal cancer. However, there are also many data proving that the incidence of colorectal cancer is not higher in schistosome-endemic areas than in other areas, and that there is no significant difference between the incidence of cancer found at sites of schistosome egg deposition and at non-schistosome egg deposition sites. In conclusion, there is no definite conclusion whether schistosomiasis enteropathy can cause colorectal cancer, but as a chronic irritant of the intestine, active treatment of schistosomiasis is still very necessary for the prevention of colorectal cancer.
12.Is colorectal tumor the same as colorectal cancer?
The colorectal tumors we usually talk about include benign and malignant. Benign tumor of the colon is also called “adenoma”, which is an excessive proliferation of colonic glands (mucus-secreting tissues in the large intestine). This is a benign tumor that is not harmful to human body. However, it is called “precancerous lesion” in medical science because it has the possibility of developing into cancer. Once this tumor is found, even though it is not malignant, it should be treated and reviewed actively.
13.How do I know if I have colorectal cancer?
The main symptom of colorectal cancer is blood in stool, followed by diarrhea, anemia, abdominal pain, weight loss and so on. Once these symptoms appear, you should go to hospital immediately. According to the statistics of domestic cases, the misdiagnosis rate of colorectal cancer is as high as 41.5%. One important reason is that people lack understanding of the symptoms of colorectal cancer, which delays the time of consultation. Some cases are also due to the lack of vigilance of the receiving doctor, who neglected to examine carefully, mistaking blood in stool for hemorrhoids and treating pus and blood as dysentery. Some people analyzed the time from symptom to diagnosis of colorectal cancer: only 8-10% of patients were diagnosed within one month, 25% of 1-3 months, and 64.3% of 3-6 months.
14.I heard that colonoscopy is very uncomfortable, is it necessary for all colon cancer screening?
For most of the people who participate in the screening, they only need to do three stool tests to see if there is blood in the stool that is invisible to the eyes (medically called “occult blood”). If this “occult blood” is present, a colonoscopy is needed to further determine if the cause of the bleeding is bowel cancer! or hemorrhoids, colitis, or polyps. If there is no such “occult blood”, colonoscopy is not necessary. Colonoscopy is not only a diagnostic tool, but also a treatment tool and a preventive tool for bowel cancer. The pain of a colonoscopy is obviously insignificant compared to having bowel cancer. As far as colonoscopy itself is concerned, it is generally not too painful unless the patient’s colon is too long or the examiner is not skilled.
15.Why do most patients who come to the hospital are already in the middle or advanced stage? What is the difference between early stage and late stage colorectal cancer treatment results?
Because early stage colorectal cancer is often asymptomatic; some patients have symptoms (even doctors) mistaken for hemorrhoids, dysentery, appendicitis and colitis. Once the disease is not cured for a long time and cancer is suspected, the disease has already reached the middle or late stage. The five-year survival rate of early stage cancer can reach 90-95% after surgery (even under colonoscopy), while the survival rate of late stage cancer is only 10%.
16.How can I get early diagnosis?
Regular screening of healthy people (health examination); necessary treatment of pre-cancerous diseases (such as treatment of adenoma and ulcerative colitis); genetic monitoring of immediate family members of colorectal cancer are the main ways to obtain early diagnosis.
17.How to conduct colorectal cancer screening?
Screening is actually a regular specialized health examination. This kind of health examination is not necessary for all people, and different subjects have different examination requirements. For example, all asymptomatic people over 50 years old should be screened once a year, and the method of screening is to do stool examination (such as occult blood test) first. People with family history of colorectal cancer should be screened from the age of 40. Those with multiple malignancies in the immediate family should undergo relevant genetic testing and necessary colonoscopy. Some families should undergo the above examinations from the age of 20-25.
18.What are the symptoms that indicate the possibility of colorectal cancer?
The common symptoms of colon cancer include blood in stool, diarrhea, abdominal pain, abdominal lumps, ascites, etc. Of course, it does not mean that if the above symptoms appear, the patient has to be diagnosed. Of course, it does not mean that you have colorectal cancer if you have the above symptoms, because many other diseases can have these symptoms. However, once these conditions appear, especially if they persist, it is important to seek medical consultation as soon as possible in order to clarify the cause and delay treatment. It should also be emphasized that many early colorectal cancers do not have symptoms, and one must not think that no symptoms means no disease.
19.Can colorectal cancer be prevented? How to prevent it?
Colorectal cancer can be prevented. There are at least two ways to prevent colorectal cancer: etiological prevention and early detection of colorectal cancer. As mentioned earlier, it is now known that bad dietary habits and benign diseases that are prone to cancer are the causes of colorectal cancer. Establishing good dietary habits, actively treating cancer-prone diseases, and receiving genetic prediction for people with clear family history of colorectal cancer are etiological prevention. Active participation in regular health checkups (screening) is an effective method for early detection of colorectal cancer.
20.How should I treat colorectal cancer?
The primary treatment for colorectal cancer is surgery. If the cancer occurs at the top of the polyp and is early, it can be removed under colonoscopy without opening the colon. If the cancer is at the root of the polyp, or if the cancer is ulcerative or suspected to have metastasis, it must be removed surgically. Surgery includes both traditional open surgery and laparoscopic surgery. The segment of the bowel with the tumor and the associated blood vessels and lymph nodes are removed. In most cases, the bowel is reconnected to maintain normal bowel function. This reattachment of the bowel is called anastomosis.
If the cancer has spread to the lymph nodes or other sites, adjuvant treatment such as chemotherapy and/or radiation therapy should be recommended. If the cancer is rectal and the tumor is located 3-5 cm from the end of the rectum, an artificial anus may be required. Rectal cancer tumor located at the end of rectum more than 5cm usually does not need artificial anus. If the rectal cancer tumor is located within 3cm of the end of the rectum, artificial anus is basically needed. The artificial anorectal fistula is located in the abdomen. In rare cases, if the tumor causes intestinal blockage, a temporary colostomy is needed.
21.About laparoscopic colorectal cancer surgery
Laparoscopic surgery is used in 90% of colorectal surgeries in developed countries in Europe and America. Compared with traditional open surgery in the past, laparoscopic colorectal cancer surgery has less trauma to patients’ tissues, less systemic reaction, less impact on immune system, less pain, faster recovery of patients, early getting out of bed, resuming diet, shortening the time of hospitalization, reducing the damage to immune system and shortening the time of postoperative recovery for patients with malignant tumors, so that they can start to implement postoperative radiotherapy, chemotherapy and other comprehensive treatments earlier. This will undoubtedly create more favorable conditions for improving the treatment effect of malignant tumors.
22.Staging of colorectal cancer
Staging provides a way to assess the chance of cure after cancer resection. Unlike other solid tumors, the size of colorectal cancer has little impact on the healing process. The staging system helps doctors to assess the extent of tumor infiltration: whether it has penetrated the bowel wall; whether it has spread to surrounding lymph nodes; and whether it has spread to distant organs or tissues. Tumors are divided into four stages. Staging is important because it can predict the chance of survival and can guide further treatment. If colorectal cancer recurs, it is usually within two years of surgery. The highest recurrence rate is within five years. stage I cancer patients have a five-year survival rate of greater than 90% and is the type with the best cure rate.
The morphology of the tumor cells under the microscope is also important in determining treatment. This morphology is called “differentiation” and tumor cells are generally classified as highly differentiated, moderately differentiated and poorly differentiated. Tumor cells that are better differentiated are more effective than those that are poorly differentiated. Staging and differentiation help doctors to decide whether to recommend radiation therapy or chemotherapy after surgery.
23.Prognosis of colorectal cancer
Assessment of long-term outcome should be based on disease staging. Patients with early stage cancer, where the tumor does not penetrate the intestinal wall and does not spread to lymph nodes or other parts of the body, have a satisfactory outcome. Those whose tumors have spread to other parts or infiltrated lymph nodes have significantly improved chances of cure after comprehensive surgery, chemotherapy or radiation therapy.