When it comes to the most commonly skipped examination during physicals, digital rectal examination (DRE) likely tops the list. The thought of a doctor inserting a finger into the anus causes significant physical and psychological discomfort for many. However, this is actually the simplest method for screening colorectal cancer, with a detection rate approaching 70%.
Rectal cancer refers to cancers occurring between the dentate line and the rectosigmoid junction. The rectum is divided into high, middle, and low rectum, with low rectal cancer being the most common, accounting for approximately 70% of all rectal cancers. Compared to colon cancer, the incidence rate of rectal cancer is 1.5 to 2 times higher.With rising living standards, both rectal and colon cancer incidence rates are increasing annually. Currently, colorectal cancer ranks third among all malignant tumors in China in terms of incidence and fifth in mortality.
Three Typical Symptoms Indicating Cancerous Changes
Early-stage rectal cancer often lacks specific symptoms, with signs appearing only when tumor progression affects bowel movements or causes ulceration. Three typical symptoms warrant attention:
First: Blood in stool. This is a common symptom of rectal cancer, caused by impaired blood supply due to rapid tumor proliferation. It results from ulceration formed by tumor tissue necrosis and breakdown, typically appearing as bright red or dark red blood.
Second, rectal irritation symptoms. These arise from the lesion stimulating the rectum, including altered bowel habits (alternating constipation and diarrhea), frequent urge to defecate, anal heaviness, and incomplete evacuation sensation (persistent urge to use the restroom without fully emptying).
Third, intestinal narrowing symptoms. Tumor progression causes intestinal stenosis, leading to narrower stools and progressively difficult bowel movements. In later stages, partial intestinal obstruction may cause abdominal pain, bloating, and other symptoms of incomplete intestinal obstruction.
Beyond these typical symptoms, rectal cancer may also present with accompanying signs.For example: Weight loss and emaciation: Malnutrition resulting from impaired digestion and absorption due to tumor progression and chronic abdominal pain/distension. Tumor infiltration symptoms: Tumor invasion of the bladder or prostate may cause hematuria, frequent urination, and urgency. Invasion of the sacral plexus may lead to fecal incontinence, persistent lower abdominal pain, and sacral discomfort. Metastatic symptoms:Metastasis to the liver, lungs, bones, etc., can cause liver dysfunction, jaundice, shortness of breath, or pain at the site of bone metastasis. What tests are needed to diagnose rectal cancer? There are several methods for screening rectal cancer. The simplest, most accessible, and critically important clinical examination is digital rectal examination (DRE).The physician inserts a finger into the patient's anus to examine for abnormalities. This typically allows detection of masses within 7 centimeters of the anal opening and assessment of their potential malignancy. It is important to remind individuals undergoing health screenings not to decline this examination due to embarrassment or discomfort, as digital rectal examination can detect nearly 70% of rectal cancers.
Patients suspected of having rectal cancer should undergo a colonoscopy, which can pinpoint the tumor's location and provide a definitive diagnosis through biopsy. Patients already diagnosed with rectal cancer should also undergo a full colonoscopy before surgery, as approximately 5%-10% of rectal cancer patients have multiple primary cancers.Multiple primary cancers, also known as recurrent cancers, refer to the simultaneous or sequential occurrence of two or more independent primary malignant tumors in one or more organs, most commonly within the digestive system. Additionally, endoscopic ultrasound can accurately assess tumor invasion depth and the status of surrounding lymph nodes.
All rectal cancer patients should undergo imaging studies—enhanced chest, abdominal, and pelvic CT scans along with rectal MRI—to determine tumor depth of invasion (T staging), lymph node metastasis (N staging), and distant metastasis (M staging). This prepares for staging assessment and appropriate treatment selection. If distant metastasis remains unclear, PET-CT may be performed.
Pathological examination serves as the gold standard, confirming tumor type and differentiation. It also enables genetic sequencing to identify tumor mutations, providing evidence for drug selection.
Blood tests, routinely performed for all patients, primarily assess general health status. Tumor markers (CEA and CA19-9) have limited utility in detecting early-stage rectal cancer but can evaluate tumor burden and monitor for postoperative recurrence.
Treatment for rectal cancer should follow an individualized, comprehensive approach. Physicians will develop the most appropriate treatment plan using multiple modalities based on the patient's general condition, disease stage, and preferences.
Very early rectal cancer (tumors confined to the mucosal layer or part of the submucosal layer): Endoscopic submucosal dissection (ESD) can achieve excellent therapeutic outcomes;Early-stage rectal cancer (no lymph node metastasis): Surgical resection can achieve curative intent; Advanced rectal cancer (lymph node metastasis): Appropriate use of radiotherapy, chemotherapy, surgery, and chemotherapy combinations may achieve curative intent in some patients; Advanced rectal cancer: Comprehensive treatment is the mainstay, employing chemotherapy, targeted therapy, immunotherapy, surgery, and radiotherapy to prolong patient survival.
Colonoscopy recommended after age 50
Can rectal cancer be prevented? Primary prevention involves avoiding high-risk factors: quitting smoking, modifying poor dietary habits, consuming fiber- and vitamin-rich foods like fruits and vegetables, reducing red meat intake, increasing physical activity to prevent obesity, and maintaining a positive mindset.Another crucial preventive measure is colorectal cancer screening. Early detection of colorectal cancer or precancerous lesions enables timely diagnosis and treatment, improving therapeutic outcomes.
We recommend initiating colorectal cancer screening at age 50. While colorectal cancer risk increases with age, so does the risk of severe complications from colonoscopy (e.g., colonoscopy-induced bowel perforation, increased cardiovascular events).Individuals aged 76 to 85 should undergo personalized screening based on underlying medical conditions, while those over 85 should discontinue screening.
Additionally, risk assessment can be conducted using China's colorectal cancer screening high-risk factor quantitative questionnaire. High-risk individuals should undergo colonoscopy as recommended by their physician. Specifically, those meeting any one or more of the following criteria are considered high-risk:
1. First-degree relative with colorectal cancer history
2. Personal history of cancer (any malignant tumor)
3. Personal history of intestinal polyps
4. Concurrent presence of two or more of the following: Chronic constipation (over 2 months annually in the past 2 years);Chronic diarrhea (cumulative duration exceeding 3 months over the past 2 years, with each episode lasting at least 1 week); Mucus-blood stool; History of adverse life events (occurring within the past 20 years and causing significant psychological trauma or distress); History of chronic appendicitis or appendectomy; History of chronic biliary tract disease or cholecystectomy.
In general, individuals aged 50 to 75 who are eligible for colonoscopy should undergo colorectal cancer screening regardless of symptoms. Patients rated as high risk or with positive fecal occult blood or fecal DNA test results based on the colorectal cancer screening risk factor questionnaire should undergo colonoscopy as recommended by their physician.