Hypothesis: Patients with stage IV colon or rectal cancer at initial diagnosis have characteristics that will predict subsequent survival time.
Design: Retrospective cohort study.
Setting: Urban county teaching hospital providing tertiary care.
Patients: Patients who came to the study institution with stage IV colon or rectal cancer between 1991-1999.
Main outcome measure: Survival duration (days) after diagnosis.
Results: One hundred five patients were identified, with a median survival of 225 days (interquartile range, 72-688 days). Univariate analysis identified carcinoembryonic antigen (CEA) and albumin (ALB) as possible predictors for survival. Classification and regression tree analysis, a form of binary recursive partitioning, was used to identify optimal cut points for CEA (275 ng/mL) and ALB (2.7 g/dL) levels. Based on the cut points, patients were stratified into the following groups: (1) low CEA, high ALB; (2) low CEA, low ALB; (3) high CEA, high ALB; and (4) high CEA, low ALB. The median survival times for the first group and the fourth group were 287 days (interquartile range, 150-851 days) and 39 days (interquartile range, 14-168 days), respectively. A Kaplan-Meier analysis was performed, and a statistically significant difference was identified across all strata (P =.004). Additionally, groups 1 and 4 demonstrated the largest overall survival difference (P<.001).
Conclusions: Patients with stage IV colon and rectal cancer with a CEA level greater than or equal to 275 ng/mL and an ALB level less than 2.7 g/dL had a significantly shorter survival time. Conversely, patients with an ALB level greater than or equal to 2.7 g/dL and a CEA level less than 275 ng/mL had a longer survival time.