Purpose: We investigated whether the initial CT distribution of metastatic disease is predictive of overall survival in patients with stage IV colorectal cancer.
Materials and methods: A retrospective study of 65 patients (37 males, 28 females, mean age 56, range 28-88 years) with stage IV colorectal cancer was derived from an institutional database. Inclusion criteria required KRAS mutation testing and pretreatment CT examinations to be available (65 abdomen/pelvis, 63 chest). Disease burden was jointly characterized by two radiologists in consensus. Median follow-up was 39 months (range 8-115 months). Survival was assessed using Cox proportional hazards models.
Results: Univariate analysis showed that stratified site(s) of measurable disease and counts of measurable lesions ≥1 cm in the liver, peritoneum, and retroperitoneum were statistically significant risk factors for overall mortality [univariate HR 8.2 (CI 2.7-25.4) for isolated peritoneal disease, HR 1.11 per 5 lesions (CI 1.05-1.17) for liver lesions, HR 1.15 per lesion (CI 1.05-1.26) for peritoneal lesions, and HR 1.11 (CI 1.03-1.19) for retroperitoneal lymph nodes ≥1 cm in short axis]. The stratified site(s) of disease and counts of measurable liver lesions remained significant in the multivariate model (p < 0.0001 for isolated peritoneal disease and count of liver lesions). Thoracic metastases were not statistically significant predictors of overall mortality in this cohort.
Conclusion: This study identified site(s) of measurable metastasis and counts of measurable liver lesions as independent predictors of overall survival. These findings may have value for future prognostic assessments once validated in a larger, independent, and potentially prospective cohort.