Which of the following recommendations for adjuvant chemotherapy of colorectal carcinoma are true?

B. Patients with Stage III or Dukes C disease should receive adjuvant treatment for 1 year with levamisole combined with 5-FU.

DISCUSSION: Some 50% to 60% of patients with colorectal cancer have tumors that penetrate the serosa or involve the regional lymph nodes, eventually recur, and end fatally. Therefore, adjuvant therapy to improve the mortality was sought for this group of patients. 5-Fluorouracil (5-FU) is the most active drug used against colon cancer, but it achieves only a 10% to 20% response in patients with advanced disease. Levamisole is thought to be an immunomodulating agent in advanced colorectal carcinoma. Randomized controlled trials of 5-FU with levamisole, levamisole alone, and surgery in patients with Dukes B2 or C colon cancer were performed and demonstrated that levamisole plus 5-FU and levamisole improve diseasefree survival for patients with Dukes B and C lesions. Subsequent analysis demonstrated that Dukes C patients receiving levamisole and 5-FU also had slightly prolonged survival. A larger, confirmatory intergroup trial was launched that demonstrated that in patients with Dukes C carcinomas of the colon, adjuvant treatment for 1 year with levamisole combined with 5-FU reduced the risk of cancer recurrence by 41% and reduced mortality overall by 33%, but the results in patients with Dukes B2 disease was equivocal.