Metastatic disease: Critical determinant of prognosis

The death rate from colorectal cancer has begun to decline somewhat in recent years, and the 5-year survival rate [Fig. 1] has improved, probably as a result of more aggressive diagnosis and therapeutics. However, the number of cases diagnosed annually has not seen a commensurate decline, nor has the incidence of metastatic disease in patients thought cured at time of primary surgery:

• Fifteen to 20% of patients with colorectal cancer present with distant metastases
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• Twenty-five percent of patients with diagnosis of colorectal carcinoma will have synchronous hepatic metastases (see image left, arrow). In another 25%, hepatic metastases will develop during the follow-up period.^, The natural history of untreated metastatic colorectal cancer to the liver is dismal, with virtually no 5-year survivors.
• In spite of having localized disease at operation, 30%-40% of patients initially classified as Dukes' B will develop metastases (see chart below)

• Fifty percent of (all) patients who undergo curative resection develop local, regional, or widespread recurrence. These statistics have remained relatively constant over several decades despite improved methods of early diagnosis & surgical treatment.
• Extrahepatic disease, lymph node involvement, and the inability to resect all gross metastases to the liver are generally considered absolute contraindications to resection for cure. No significant improvement in median survival has been demonstrated in this patient population.

Thus, if the prognosis of colorectal cancer is to be significantly impacted — and if patients are to be spared unproductive and risky attempts at curative operations due to unrecognized metastatic disease — physicians and surgeons must be better equipped to

• Diagnose colorectal cancer earlier, when it is least likely to have metastasized.
• Detect, localize, resect and treat metastatic disease earlier in the course of the disease, when adjuvant therapies are most efficacious.
• More accurately stage patients not resectable for cure, so they can be referred for palliative and potentially life-extending chemotherapeutic and radiation treatments when they are likely to be most beneficial.

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