Clinical manifestations of rectal cancer

As part of the large intestine, the rectum shares many of the same clinical symptoms as the colon. However, as the anatomical site at the end of the digestive tract, rectal cancer has its own characteristic symptoms.

1. Blood in the stool This is the most common symptom of rectal cancer, and it is also the symptom that is most easily ignored by patients. Sometimes doctors do not conduct a careful examination of the patient, and it is not uncommon to misdiagnose bloody stools caused by rectal cancer as hemorrhoids. The blood in the stool of patients with rectal cancer is often a small amount of dark red blood, which can be mixed with stool or appear alone in the form of blood, and is often not accompanied by changes in bowel habits. Patients often show: frequent and urgent bowel movements, and defecation becomes the first thing in daily life. Therefore, it is called "morning diarrhea", but in fact it is not real diarrhea because there is no stool-like discharge. It should be pointed out that this symptom does not only appear in the early morning, but can also appear frequently during the day and at night. 80%-90% of rectal cancers have blood in the stool. Sometimes pus and blood in the stool or blood clots and necrotic tissue can be seen, which are often misdiagnosed as hemorrhoids or dysentery and ignored.

2. Pain When the tumor grows and causes rectal obstruction, abdominal pain may occur. When the tumor invades surrounding organs (such as the sacral plexus at the back), it may manifest as pain in the sacral region or sciatic nerve distribution area. If the tumor invades the anal canal or perineal skin downward, severe perineal pain may occur.

3. Rectal irritation symptoms include frequent urge to defecate and change in bowel habits; a feeling of falling in the anus before defecation, tenesmus, and a feeling of incomplete defecation. When the cancer invades and causes intestinal stenosis, the stool will initially become deformed and thinner; when it causes partial intestinal obstruction, there will be abdominal pain, bloating, hyperactive bowel sounds and other manifestations of incomplete intestinal obstruction.

4. Manifestations of tumor invasion of adjacent structures The adjacent structures around the rectum are complex. Invasion of the anal canal by cancer of the lower rectum may cause local pain in the anus. If the anal sphincter is affected, anal incontinence, bloody stools, and masses may protrude from the anus. Cancer invasion of the prostate and bladder may cause frequent urination, painful urination, and hematuria. If it penetrates the bladder wall to form a recto-vesical fistula, feces and gas may appear in the urine, causing refractory urinary tract infection. Invasion of the posterior wall of the vagina in women may cause increased leucorrhea. If it penetrates, a recto-vaginal fistula may form, and feces and mucus, pus and blood may appear in the vagina. Tumors on the posterior wall of the rectum may penetrate the intestinal wall and invade the pelvic wall, sacral plexus, and sacrum, causing persistent and severe pain in the sacrum and coccyx. After the tumor invades the anal canal, it may metastasize to the inguinal lymph nodes, causing inguinal lymphadenopathy. In the late stage, liver metastasis may cause ascites, hepatomegaly, jaundice, anemia, weight loss, edema, cachexia, etc. The frequency of symptoms is as follows: blood in stool 80%-90%, frequent stool 60%-70%, thin stool 40%, mucous stool 35%, anal pain 20%, tenesmus 20%, and constipation 10%.