Subtypes of minimal residual disease and outcome for stage II colon cancer treated by surgery alone.

INTRODUCTION: Twenty-five percent of stage II colon cancer (CC) patients relapse within 5 years due to minimal residual disease (MRD) not eliminated by surgery. We hypothesise that subtypes of MRD, defined by circulating tumour cells (CTCs) and bone marrow micrometastasis (mM), have different types and kinetics of relapse. METHODS AND PATIENTS: One month after surgery, blood and bone marrow samples were taken to detect CTCs and mM using immunocytochemistry with anti-carcinoembryonic antigen (CEA). Follow-up was for up to 5 years or relapse. Disease-free survival curves using Kaplan-Meier (DFS) and restricted mean disease-free survival times (RMST) were calculated for three prognostic groups: A: MRD (-), B: mM (+) CTC (-) MRD and C: CTC (+) MRD. RESULTS: One hundred and eighty-one patients (82 men) have participated, mean age was 68 years and median follow-up was 4.04 years (A (N = 105), B (N = 36) and C (N = 40)). For the whole cohort of 5 years, DFS was 70%, median DFS has not reached (Groups A: 98%, B: 63% and C: 7%) and median DFS for Groups A and B have not reached. RMST for the whole cohort of 4.1 years, Group A was 4.9 years, B was 4.1 years and C was 1.7 years. Serum CEA was significantly higher in Group C. No significant differences for sex, age or high-risk adverse prognostic factors between groups were detected. CONCLUSIONS: MRD subtypes define relapse patterns and may be useful to define the risk of relapse in stage II CC patients, in which patients may benefit or not from additional therapy and warrants further studies with a larger number of patients.

Secondary Circulating Tumor Cells (CTCs) but not Primary CTCs are Associated with the Clinico-Pathological Parameters in Chilean Patients With Colo-Rectal Cancer.

BACKGROUND: The aim of this study was to assess detection of circulating tumor cells (CTC) using anti-CEA pre and post surgery in Chilean patients with colo-rectal cancer. MATERIALS AND METHODS: The presence of CTCs was evaluated in 80 colorectal cancer patients pre and post surgery using standard immunocytochemistry and the results were compared with findings for standard clinico-pathological parameters. RESULTS: In patients pre- surgery CEA (+) CTCs were frequently found, with no relation to tumor size or nodal status. After surgery, the presence of CTCs was associated with such clinico-pathological parameters. The frequency of CTC detection in node positive patients did not change after surgery. In patients with metastasis there was also no change in the frequency of CTC detection, and clusters of 3 or more CTCs were evident. CONCLUSIONS: Secondary CTCs are associated with clinico-pathological parameters only after surgical removal of the primary tumor, and might be important in identifying patients at high risk of relapse. Primary CTCs detected before surgical removal are frequently found, are not associated with the clinico-pathological parameters and might have a role in cancer screening. These findings suggest the need for studies with a larger population of patients.