Title:
Post-treatment surveillance of patients with colorectal cancer with surgically treated liver metastases.

Abstract:
Little is known about current surveillance patterns after treatment of colorectal liver metastasis (CRLM) or whether the intensity of surveillance correlates with outcome. We sought to define current population-based patterns of surveillance and investigate whether intensity of surveillance impacted outcome.
We queried the Surveillance, Epidemiology, and End Results-linked Medicare database for patients with CRLM diagnosed between 1991 and 2005 who underwent liver resection and/or tumor ablation. Frequency of post-treatment abdominal computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET) was recorded for ≤ 5 years after treatment. The association between frequency of imaging with secondary interventions and long-term survival were analyzed.
We identified 1,739 patients with CRLM treated with surgery; median age was 73 years, and the majority were male (52.6%). CRLM treatment consisted of liver resection (61%), ablation (32%), or both simultaneously (6%). CT (97%) was utilized more often for post-treatment surveillance compared with MRI (7%) and PET (18%). A temporal trend was noted with more frequent surveillance imaging obtained in post-treatment year 1 (2.4 scans/year) versus year 5 (0.6 scans/year; P = .01); 66% of living patients had no imaging after 2 years. Frequency of surveillance imaging correlated with procedure type (total number of scans/5 years: resection, 5.0; ablation, 4.6; resection and ablation, 6.2; P = .01). Other factors associated with a greater frequency of surveillance included younger age at diagnosis, geographic location in the South, and CRLM directed surgery in 2000 through 2005 (all P < .05). Overall survival did not differ by intensity of surveillance imaging (3-4 scans/yr, 43 months vs 2 scans/yr, 57 months vs 1 scan/yr, 54 months; P = .08).
Marked heterogeneity exists in how often surveillance imaging is obtained after treatment of CRLM. Intensity of imaging does not affect time to second procedure or median survival duration. Surveillance guidelines for CRLM need to be refocused to provide the best value for healthcare resources.