Colonic or Rectal cancer Treatment

Resection of the primary colonic or rectal cancer is the treatment of choice for almost all patients who have resectable lesions and can tolerate general anesthesia. Multiple studies demonstrate that minimally invasive, laparoscopically assisted colectomy results in similar outcomes and rates of recurrence to open colectomy. Regional lymph node dissection should be performed to determine staging, which guides decisions about adjuvant therapy. Even patients with extensive metastatic disease may benefit from resection of the colonic tumor to reduce the likelihood of intestinal obstruction or serious bleeding.

For rectal carcinoma, the operative approach depends on the level of the tumor above the anal verge, the size and depth of penetration, and the patient's overall condition. Clinical staging by endorectal ultrasound or MRI with endorectal coil is important in guiding the clinical approach. In carefully selected patients with small, mobile (< 4 cm), well-differentiated T1 or T2 rectal tumors that are less than 8 cm from the anal verge and that appear on endosonography to be localized to the rectal wall, transanal excision may be performed. This approach avoids laparotomy and spares the rectum and anal sphincter, preserving normal bowel continence. All other patients will require either a low anterior resection with a colorectal anastomosis or an abdominoperineal resection with a colostomy, depending on how far above the anal verge the tumor is located and the extent of local tumor spread.

Careful dissection of the entire mesorectum at the time of surgery has been shown to reduce local recurrence to 8%. With improvements in surgical stapling techniques, it is possible to perform low anterior resection provided there is a margin of at least 2 cm of normal tissue below the tumor. Although low resections obviate a colostomy, they are associated with increased immediate postsurgical complications (leak, dehiscence, stricture) and defecatory complaints (increased stool frequency, defecatory problems, and incontinence). With unresectable rectal cancer, the patient may be palliated with a diverting colostomy, laser fulguration, or placement of an expandable wire stent.

A. Adjuvant Therapy for Colon Cancer

Adjuvant chemotherapy and radiotherapy have been demonstrated to improve overall and tumor-free survival in selected patients with colon cancer.

1. Stage I - Because of the excellent 5-year survival rate (90-100%), no adjuvant therapy is recommended.

2. Stage II (node-negative disease) - The expected 5-year survival rate is 80%. A benefit from adjuvant chemotherapy has not been demonstrated in most controlled trials for stage II colon cancer (see discussion for stage III disease). However, otherwise healthy patients with stage II disease that is at higher risk for recurrence (perforation, T4, poor differentiation on histology) may benefit from adjuvant chemotherapy.