Generally speaking, the incidence of colorectal cancer increases rapidly with age. Residents in Shanghai urban areas are from 45 to 75 years old, and the incidence of colorectal cancer more than doubles for every 10 years of age. Therefore, colorectal cancer is more likely to occur in middle-aged and elderly people. The median age of colorectal cancer patients in China is about 50 years old, about 15 years earlier than reported in Europe and America. Colorectal cancer patients under the age of 40 in Europe and the United States are rare, generally accounting for only 2.2%~4.5%; although in the low-incidence area of colorectal cancer in China, 50% of colorectal cancer can be found through simple and easy digital rectal examination, 75%~ The concept that 80% of colorectal cancers can be detected by ordinary hard tube sigmoidoscopy should still be emphasized repeatedly. However, with the increase in the incidence of colorectal cancer, there is also an understanding of the law of the onset of the disease in the proximal large intestine. Therefore, it is increasingly important to use fiber colonoscopy to check the entire large intestine.
Colorectal adenomas have multiple tendencies, so colorectal cancers from their malignant transformations also have multiple primary tendencies that are more common than other organs. In the literature, 2%-9% of colorectal cancer patients have multiple primary colorectal cancers (multiple primary cancers in patients with familial adenoma and ulcerative colitis are not included in the statistics). According to statistics, when colorectal cancer occurs in patients with these two types of diseases, 50% and 26% of the patients have multiple primary colorectal cancers. Multiple primary colorectal cancers can occur at the same time or at different times. Generally, several primary cancers are diagnosed at the same time, or the diagnosis interval is within 6 months, which is called "simultaneous multiple primary colorectal cancer". When several cancers are diagnosed more than 6 months apart, they are called "multiple primary colorectal cancer at different times." The time from the onset of symptoms to the confirmation of the diagnosis is called the "disease course". The length of the disease of colorectal cancer patients varies greatly. Since about 80% of colorectal cancers evolve from adenomas, it takes about 10 years on average to evolve from adenomas to cancer. Some adenomas, especially those located in the rectum and sigmoid colon, often have symptoms such as blood in the stool and mucus. These symptoms can occur intermittently, repeat for many years, and eventually develop into cancer. The course of these patients can be as long as several years. Patients and doctors often mistaken for hemorrhoids, chronic colitis, etc. because of the long course of the disease, without doubting the possibility of tumors. On the other hand, many adenomas, especially those located in the proximal colon, have no obvious symptoms, even until they become cancerous. Among asymptomatic colorectal cancer, 1/4 of the patients are late, so clinicians can't take it lightly for those with symptoms.
Most early colorectal cancers have no obvious symptoms, or show symptoms of precancerous lesions. As the disease progresses, a series of symptoms and signs appear. Common clinical manifestations of colorectal cancer are blood in the stool, mucus and blood in the stool, changes in bowel habits, abdominal pain, abdominal mass, ascites, intestinal obstruction, anemia, etc. The clinical manifestations of colorectal cancer in different parts are different: ①Right colon cancer, due to the wide intestinal cavity, loose stools, intestinal obstruction is rarely seen, blood in the stool is rare, and abdominal masses; anemia, weight loss, fatigue Relatively common. It is worth noting that the abdominal mass in right colon cancer is not entirely the tumor itself. It is often the adhesion mass caused by the tumor co-infection, or even perforation, and sometimes the intussusception caused by the mass. The latter case is often It manifests as a looming abdominal mass. ②Left colon cancer, especially sigmoid colon cancer, where the intestinal cavity is tortuous and relatively narrow, and the stool has already formed at this time, so it is more likely to cause intestinal obstruction. Since the bleeding covers the surface of the stool after the tumor ruptures in this part, it is easy to be noticed by the patient, so blood in the stool is more common in left colon cancer. The amount and characteristics of blood in stool are often related to the location of the tumor. The closer the lesion is to the anus, the more fresh the blood color is, and the separation of blood and stool is often; The stool of high-level colorectal cancer is often jam-like. It should be pointed out that in patients with colorectal cancer who have blood in the stool for the first time after the age of 40, the lesions of 2/3 are still limited to the intestinal wall. Therefore, as long as you are vigilant and check in time, you can still get a better prognosis. Changes in bowel habits are also common symptoms of colorectal cancer, such as diarrhea or diarrhea, alternating constipation, etc. When the lesion is close to the anus, there is often tenesmus.
In addition to the symptoms of the tumor itself, the complications of colorectal cancer, such as fistulas between the large intestine and adjacent organs, low fever due to tumor necrosis, hepatomegaly and ascites due to tumor metastasis, and neurological symptoms due to brain metastasis It is often the clinical manifestation of advanced colorectal cancer. It is worth emphasizing that rectal cancer in China accounts for about 50% of colorectal cancers, and a simple digital rectal examination can obtain diagnostic clues. Therefore, digital rectal examination should be regarded as a routine physical examination.
Due to patients' lack of understanding of the symptoms of colorectal cancer, many patients have symptoms that have persisted for a long time before going to the hospital. However, there are still a considerable number of patients whose diagnosis is delayed by doctors.
Some misdiagnosed cases are due to the fact that the doctor only diagnoses on the basis of symptoms and does not perform examinations. Although some have done related examinations, they have overlooked the co-existing colorectal cancer due to the discovery of coexisting benign diseases. For example, patients with blood in the stool undergo proctoscopy to find hemorrhoids, but have not performed the proximal large intestine examination, and missed the concurrent high-level large intestine cancer. Statistics show that the average misdiagnosis rate of colorectal cancer in China is 41.5%. In order to improve the diagnosis rate of colorectal cancer, it should be clinically differentiated from the following diseases.
1) Bacterial dysentery: Bacterial dysentery accounts for 1/2 of the misdiagnosed diseases. Rectal cancer ulceration or co-infection can cause different degrees of pus and blood in the stool, increased stool frequency, and even tenesmus. These symptoms are almost the same as the clinical manifestations of bacillary dysentery and are easy to be confused.
2) Hemorrhoids: Hemorrhoids account for about 1/3 of misdiagnosed cases. Hematochezia is the most common clinical manifestation of left colon cancer and rectal cancer. This type of bleeding is difficult to distinguish from bleeding from hemorrhoids. In terms of prevalence, hemorrhoids are a common disease. The so-called "nine hemorrhoids in ten men", it is easy to think of "hemorrhoids" first when seeing blood in the stool, especially when hemorrhoids are seen on anal examination. Concomitant rectal cancer.
3) Ulcerative colitis: The number of patients with ulcerative colitis has increased in recent years. Its common symptoms such as bloody stools, pus and bloody stools, increased stool frequency and abdominal discomfort, even weight loss, anemia, etc. are also common symptoms of middle and advanced colorectal cancer. Severe long-term unhealed ulcerative colitis itself also has a higher cancer rate. Once cancerous, even under colonoscopy, it is difficult to distinguish which lesions are inflammation, ulcers, and which lesions have become cancerous.
4) Appendicitis or abscess around appendix: Appendicitis, abscess around appendix, and ileocecal mass formed after appendicitis are diseases that are easily misdiagnosed for cecal cancer. Cecal cancer and part of the ascending colon cancer often present with pain in the right lower abdomen, tumor ulceration or combined infection, fever, elevated white blood cells, and even masses in the right lower abdomen. Because appendicitis and abscess around appendix are frequently-occurring, it is easy for people to mistake cecal cancer for appendicitis or abscess around appendix.
5) Intestinal tuberculosis: The main symptoms of some patients with colorectal cancer are changes in bowel habits such as diarrhea and constipation, accompanied by low-grade fever and weight loss, which can easily be misdiagnosed as intestinal tuberculosis.
6) Other diseases: such as upper right abdomen pain due to liver flexure of the colon. At the time of consultation, B-ultrasound found "gallbladder stones", but the stones were removed but colon cancer remained in the abdomen. Another example is colorectal cancer with insignificant symptoms but ovarian metastasis, which can be misdiagnosed as "primary ovarian tumor" in gynecology and the metastasis is removed, but the primary colorectal cancer is still left in the abdomen. In addition, the possibility of colorectal cancer should also be considered in the differential diagnosis of intestinal obstruction and acute peritonitis. In order to avoid misdiagnosis, in the diagnosis and treatment of colorectal cancer, the following principles should be mastered: strengthen the publicity of colorectal cancer prevention and treatment, improve the self-awareness of patients, pay attention to the identification of symptoms and necessary digital rectal examination and colonoscopy; pay attention to exclude certain bowel Benign lesions with colorectal cancer; strengthen the follow-up of precancerous lesions and the screening of asymptomatic high-risk groups.