Preoperative staging CT thorax in patients with colorectal cancer: Its clinical importance

Background: Recent studies suggest that there is little benefit to routine preoperative staging CT of the thorax in colorectal cancer. Objective: The current study hypothesized that staging CT of the thorax is not mandated in all patients with colorectal cancer. Design: This study was a tertiary-care center retrospective observational study. Patients: Patients with a diagnosis of colon and rectal adenocarcinoma during 2006 to 2011 were included in a hospital database. Demographic, pathological, radiological, survival, and clinical factors were recorded. Three hundred eighty-two patients were included in the analysis (234 male, 148 female). Interventions: All patients underwent preoperative staging CT of the thorax to determine the presence of pulmonary metastasis and/or indeterminate lesions. Main Outcome Measures: Patients demographics were reviewed, and the factors associated with pulmonary metastasis and indeterminate lesions were evaluated. Results: Distant metastases were evident in 61 patients (16%). CT scans revealed pulmonary metastasis in 23 patients (6%), and indeterminate lesions in 33 (8.6%). Only one-third of pulmonary lesions were evident on chest x-ray. On logistic regression analysis, nodal positivity was associated with an increased risk for pulmonary metastasis (p = 0.03). There was no difference in overall survival between patients with pulmonary metastasis and indeterminate lesions (p = 0.35, Kaplan- Meier estimate, log rank analysis). Pulmonary metastasis developed during postoperative surveillance in 7 patients with indeterminate lesions (21.2%). Limitations: This is a retrospective, single-center study with a relatively small sample size. Conclusions: Pulmonary metastasis is relatively rare in colorectal cancer, and staging CT of the thorax may not be mandated in low-risk patients.