Since the appearance of effective new drugs for colorectal cancer and more aggressive surgical approaches to resecting isolated metastases, many patients who had metastatic cancer are now free of disease for an extended period of time. There are few guidelines on how to follow such patients it is fairly new situation and there are no mature studies. For high risk non-metastatic colon cancer, NCCN guidelines recommend annual CT of chest, abdomen and pelvis. Post-surgery surveillance is similarly warranted following resection of isolated colorectal cancer metastases because a minority of the recurrent patients can be treated with metastatectomy from the liver and lung, and some of them will enjoy long-term survival and even cure. The liver is the only site of recurrence in approximately 35 to 40 percent. Five-year survival rates up to 43 percent are reported following repeat liver resection for a second recurrence, with acceptable morbidity and perioperative mortality. Clearly, these patients need to be followed so as to intervene early after new metastases appear.
The impact of CT-based follow-up for the detection of resectable disease recurrence was addressed in a review of 705 patients who underwent resection of isolated colorectal cancer liver metastases at a single institution over a 14-year period. All were followed with a similar surveillance protocol, which included outpatient clinical examinations at 3, 6, 12, 18, and 24 months, and annually thereafter, with measurement of CEA and CA 19-9 levels at each visit. In addition, all patients had CT of the thorax, abdomen and pelvis every three months for the first two years, at six monthly intervals for three more years, then annually from year six to ten.
Of the 444 patients with a recurrence diagnosed on a surveillance CT, 404 were detected within two years. The site of recurrent disease was liver only in 36 percent, outside of the liver only in 38 percent, and both in the liver and in other organs in 26 percent. The authors did not report how many recurrences were detected by serum tumor markers versus CT scans.
In total, recurrent disease was treated surgically in 124 patients. At every time point (within one year of original surgery, one to two years, beyond two years), those patients treated by liver and/or lung resection had significantly better median survival than did those who received palliative chemotherapy alone. The mean number of scans performed per resectable recurrence was 35.3, and the cost per life-year gained was £2883, a value that compares favorably to other cost-effectiveness ratios that are considered acceptable in the US and elsewhere. UPTODate recommends the following surveillance strategy for patients with stage IV disease who are rendered surgically NED (no evidence of disease):
CEA every three months for two years, then every six months for three to five years
- CT of the chest/abdomen and pelvis every three to six months for two years, then every 6 to 12 months up to a total of five years
- Colonoscopy in one year; if no advanced adenoma repeat in three years, then every five years; if advanced adenoma is found, repeat in one year
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