Rectal Cancer (RC)

A. Diagnosis

• Male/female ratio: 1.5

• Age: Rare before 40, common after 70. Most common age is 40-45, increasing to 75, then decreasing.

• Diagnosis: Performed when symptoms are present or in high-risk groups.

1. Mild bowel disturbances

• Mucus in stool

• Rapidly worsening constipation

• Feeling of urge to defecate and rectal fullness

2. Digital rectal examination (DRE)

• Valuable for tumors 7-12-15 cm from the anus.

• Combined with other tests.

• Assess the extent of RC spread.

• Clinically reliable for small RC.

3. Barium enema

• Examines the entire rectum, sometimes with double contrast technique.

• Sensitive to lesions > 5 mm.

• Overall sensitivity 55-85% for Dukes A, B stages.

• Commonly used in RC diagnosis.

4. Rectal endoscopy and biopsy

• The definitive and ideal investigation for rectal tumors.

5. Magnetic resonance imaging (MRI), computed tomography (CT scan)

• …

6. Fecal occult blood test (FOBT)

• Only for screening and early detection of RC.

7. Other tests

• Using Cr51 or Fe59 labeled isotopes.

• Porphyrin detection using labeled substances.

• Immunological methods (higher sensitivity, lower specificity).

• Fecal hemoglobin detection.

• These tests are used in high-risk patients and have certain value.

8. Ultrasound

• Limited due to bowel gas.

• Suggestive when thickened rectal wall is found.

• First-line modality for assessing liver metastases.

• Sensitivity 92%, specificity 96% for liver metastases > 15 mm.

9. Endoscopic ultrasound (EUS)

• Detects small tumors.

• Assesses tumor invasion through the rectal wall and lymph nodes.

• More effective than CT in staging T, N of RC.

B. Management

1. Surgical treatment

• Evaluate the extent of RC invasion before surgery.

• Principle: Tumor removal to achieve radical cure.

• Removal methods depend on tumor location:

• High RC (12-18 cm): Abdominal rectal resection.

• Low RC (< 6 cm): Abdominoperineal resection (today, sphincter-saving techniques are more common due to early detection and adjuvant therapy).

• Intermediate RC (6-12 cm): Choosing a rectal resection method requires careful consideration.

2. Adjuvant therapy

• Radiation therapy: No superior protocol exists.

• Controls the spread of RC.

• Used after surgery if RC is not completely removed.

• According to recommendations, preoperative radiation therapy helps eliminate cancer cells, confines the tumor, increases the possibility of removal and sphincter preservation, and reduces recurrence.

• Five-year recurrence rate with preoperative radiation therapy is very low (1.8%).

• Chemotherapy: 5 FU, Folic Acid, Levamisole.

• Indicated for liver metastases, usually given on the 5th day after surgery.

3. Postoperative follow-up and treatment

• Rectal endoscopy or barium enema: Every 2-3 months for the first 6 months, every 6 months for the next 2 years, and annually thereafter.

• Blood tests (carcinoembryonic antigen), liver ultrasound: Every 3 months for the first 2 years, every 6 months for the next 2 years, and annually thereafter.

• Chest X-ray: Every 6 months for the first 2 years, and annually thereafter.

Other key points:

• DRE: Assesses rectal lesions and the extent of spread.

• Barium enema: Examines the entire rectum, sensitive to lesions > 5 mm, overall sensitivity 55-85% for Dukes A, B stages.

• Rectal endoscopy and biopsy: The definitive and ideal investigation for RC.

• Ultrasound: Suggestive when thickened rectal wall is found, first-line modality for assessing liver metastases.

• EUS and MRI: The best imaging methods for staging T, N of RC.

• Principle of surgical treatment: Complete removal of the tumor and adjacent invaded tissues.

• Basic principles of surgery: Release the rectum and surrounding tissues first, then restore gastrointestinal continuity.

• Total rectal resection and colostomy: When sphincter preservation is not possible or the tumor is located too low.

• Preoperative adjuvant radiation therapy: Helps eliminate cancer cells, confines the tumor, increases the possibility of removal and sphincter preservation, and reduces recurrence.

• Chemotherapy: Used in cases of liver metastases.

• Postoperative follow-up: Rectal endoscopy, barium enema, blood tests, liver ultrasound, chest X-ray.