Creasy JM, et al. - In patients undergoing potentially curative resection of colorectal liver metastases (CRLM), researchers investigated the impact of primary tumor location on overall survival (OS), recurrence-free survival (RFS), and long-term outcomes. In the study participants, left-sided primary tumors were associated with improved median OS. However, primary location seemed to have no significant influence on long-term survival and recurrence-free survival. A prolonged clinical course was evident among patients with left-sided primary tumors, suggesting more indolent biology.

Methods

• For initial resections for CRLM, researchers searched a single-institution database from 1992 to 2004.
• They performed chart review to determine primary tumor location (right = cecum to transverse; left = splenic flexure to sigmoid).
• Exclusion of rectal cancer (distal 16 cm), multiple primaries, and unknown location was performed.
• They used Kaplan–Meier and Cox regression methods.
• For this study, cure was defined as actual 10-year survival with either no recurrence or resected recurrence with at least 3 years of disease-free follow-up.

Results

• Researchers included 907 patients.
• Patients were followed for a median period of 11 years.
• Left-sided primaries were identified in 578 patients (64%) and right-sided primaries in 329 (36%) patients.
• Patients with a left-sided primary showed median OS of 5.2 years (95% confidence interval [CI] 4.6–6.0) vs 3.6 years (95% CI 3.2–4.2) for right-sided (p=0.004).
• Multivariable analysis revealed that the hazard ratio for right-sided tumors was 1.22 (95% CI 1.02–1.45, p=0.028) after adjusting for common clinicopathologic factors.
• Stratified by primary location, median RFS was marginally different (1.3 vs. 1.7 years; p=0.065).
• Multivariable analysis suggested no significant association of location of primary with RFS (p=0.105).
• Observations revealed cure rates of 22% for left-sided and 20% for right-sided tumors.