A solitary implant or a small number of implants in the liver can be resected at that time or subsequently. A single pulmonary nodule is usually resected because it may be a new primary cancer of the lung rather than a metastatic focus from the colon. Residual disease after surgery may also be suspected if a preoperative CEA level has not fallen to normal in spite of the absence of gross residual disease observed at the time of surgery or on postoperative imaging. Recurrent colon cancer is usually outside the bowel. Rarely, primary anastomotic recurrences are found after low anterior resections.
Anastomotic recurrences are usually secondary to intra-abdominal recurrent tumor.
Recurrent cancer that is nonresectable is usually treated with 5-fluorouracil, which is the most active agent, in combination with another agent, usually leucovorin. Other agents are used less successfully. Radiation therapy is usually reserved for painful pelvic or bone disease and for the less common brain metastases. Patients who present initially with metastatic incurable disease may nevertheless have surgery offered, especially if the primary colon cancer is associated with bleeding or obstruction, provided that the patient has a reasonable performance status.