Objective: To determine epithelial cell dissemination in patients with localized colorectal cancer.
Design: Prospective observational study.
Setting: Academic hospital.
Participants: Two hundred twenty-two patients operated on for colorectal cancer.
Main outcome measures: Epithelial cell dissemination was determined using immunohistochemistry or cytology in histologically negative lymph nodes, the peritoneal cavity, and bone marrow. Prognostic significance was determined in relation to 140 clinicopathological variables. Median follow-up was 61 months.
Results: Of 140 patients who underwent curative surgery; 25 (17.9%) died of cancer-related causes; 10 (7.1%), of other causes; and 11 (7.8%) developed local recurrence. Tumor cells were present in the peritoneal cavity of 22% of patients, but this finding had only borderline influence on disease-free survival (P = .07). Lymph node micrometastases correlated with T category but not with survival. The presence of epithelial cells in the bone marrow was detected in 64% of patients but was not associated with tumor stage or survival. Multivariate analysis failed to identify occult tumor cell dissemination into any body compartment as an independent prognostic factor of disease-free survival.
Conclusions: Tumor cells disseminate into various body compartments in early stages of disease. In about two-thirds of patients, tumor cells are left in the body after so-called curative surgery. However, the presence of minimal residual disease has no independent prognostic significance in relation to established risk factors for tumor progression. Thus, other factors, such as the presence of a cellular metastatic phenotype and/or ineffective immunological response, must play an important role.