Aim: The aim of the study was to detect minimal residual disease (MRD) in bone marrow samples, portal and peripheral blood samples collected from colorectal carcinoma (CRC) patients, and to assess the results in relation with clinical stages of the disorder and to evaluate potential correlation between the MRD presence and the disease relapse and overall patient survival rates.
Material and methods: The study included patients with primary CRCs indicated for laparoscopic resections. From September 21, 2006 to December 31, 2008, the authors selected 159 subjects with median age of 56. 126 patients (79.25%) were operated for CRC stage I-III, 33 patients (20.75%) had CRC stage IV. Six samples were collected in each subject to detect the MRD presence (systemic venous blood and bone marrow at the beginning of the procedure, venous blood from the mesenteric bed, systemic venous blood after the resection procedure, systemic venous blood and bone marrow one month after the procedure), as well as samples of the tumor tissue. Real-time RT-PCR method was use to detect the MRD.
Results: The study confirmed correlation between MRD positivity in preoperative bone marrow samples and the disease stage (p < 0.035). It showed correlation between findings in preoperatively collected systemic venous blood samples and in mesenteric venous blood samples (p < 0.003), correlation between findings in systemic venous blood samples collected after the resections procedures and in systemic venous blood samples one month after the procedure (p < 0.015), as well as correlation between findings in preoperative systemic venous blood samples and findings in systemic venous blood samples collected after the procedures (p < 10(-5)). The authors found out that the surgical procedure affected the MRD presence in systemic venous blood samples in primary negative patients (p < 0.025). During the study period, the authors revealed no statistically significant correlation between the MRD findings in stage I-III patients and their disease-free survival (p < 0.59). Considering the above results, possible direct correlation between positive MRD findings in systemic venous blood samples, which were collected preoperatively in CRC stage I-III patients, and reduced survival time is expected (p < 0.075). During the study period, the overall survival time was significantly reduced in stage I-III patients with positive findings in postoperative systemic venous blood samples, compared to that in negative patients (p < 0.004).
Conclusion: The data suggest certain correlations between the MRD findings and the disease prognosis. The authors continue to collect further samples and assess the outcomes in order to enlarge the patient study group and the data, and plan to evaluate the outcomes in a 5-year to 10- year follow up period.