Diagnostic basis of rectal cancer

Rectal cancer is caused by the malignant transformation of rectal tissue cells. With the improvement of the quality of life, the incidence of rectal cancer has increased year by year. According to experts, the incidence of colorectal cancer (colon cancer + rectal cancer) ranks third (the first two are lung cancer and stomach cancer). By 2015, the incidence of colorectal cancer may exceed that of lung cancer and stomach cancer. Therefore, for patients with rectal cancer, accurate diagnosis is very necessary for the treatment of patients.

1. Rectal digital examination: Rectal digital examination is simple and easy to perform. Rectal digital examination is still the most basic and important examination method in a series of examinations before rectal cancer surgery.

2. Laboratory Examination

1. Fecal occult blood test: This method is simple and easy to use. It is a preliminary screening method for colorectal cancer and a routine examination for colon diseases. If conditions permit, immunological methods can also be used to improve the accuracy rate.

2. Hemoglobin examination: Patients with unexplained anemia and hemoglobin levels below 100g/L should be recommended to undergo barium enema examination or fiber colonoscopy.

3. Serum carcinoembryonic antigen (CEA) test: CEA test does not have specific diagnostic value and is therefore not suitable for general screening or early diagnosis, but it is helpful in estimating prognosis, monitoring efficacy and recurrence.

3. Endoscopic examination: Patients with blood in stool or changes in bowel habits who have no abnormal findings during rectal examination should undergo routine sigmoidoscopy or fiber colonoscopy. Endoscopic examination can directly observe the lesions and take biopsies for pathological diagnosis. Fiber colonoscopy is currently the most effective, safest and most reliable method for diagnosing colorectal lesions. Most early colorectal cancers can be found by endoscopic examination.

4. Double contrast imaging: Traditional barium enema X-ray examination has a high detection rate and diagnostic accuracy for early colorectal cancer and small adenomas, and has now become a routine examination in the radiology department.

5. CT diagnosis: CT cannot be used as an early diagnosis method, but CT is of great significance for the staging of colon cancer, especially for patients who are estimated not to be able to undergo direct surgery but may be surgically removed after external radiation or local intracavitary radiotherapy. CT is of great significance for the surgical estimation of advanced rectal cancer and recurrent rectal cancer. It can directly observe the invasion of tumors into pelvic muscles (levator ani, obturator internus, coccygeus, piriformis, gluteal muscles), bladder and prostate. A pelvic CT examination can be performed 3 months after surgery as a basic film for comparison during follow-up. A CT examination should be performed every 6 to 8 months within 2 to 3 years after surgery, or a CT examination should be repeated when CEA is elevated. In addition, CT can provide correct positioning for the use of radiotherapy for recurrent rectal cancer and determine the appropriate target volume.