Long-term Follow-Up of Bone Marrow Micrometastases in Colon Cancer Patients.

3529 Background: There is suggestive evidence from investigations with short follow-up that bone marrow (BM) micrometastases are a poor prognostic factor in colorectal cancer patients. The objective of the present prospective study was to evaluate the long-term prognosis of bone marrow micrometastases (BMM) in a large cohort of colon cancer patients. Methods: Overall, 144 stage I-III colon cancer patients underwent BM aspirations from both iliac crests prior to open oncologic colon resections. The BM aspirates were stained with the pancytokeratin antibody A45-B/B3, and analyzed for the presence of epithelial tumor cells by an automated cellular imaging system and by visual verification by a pathologist. Overall (OS) and disease-free survival (DFS) were analyzed by Cox proportional hazard regression analyses. Results: Median age was 74 years, 47% of patients were female. BMM were found in 55 patients (38%). Median follow-up was 74 months (87 months for patients who survived) with no loss to follow-up. Overall, 30 patients (21%) had a recurrence and 56 patients (39%) died. In univariate analyses, BMM-positive patients had a significantly worse OS (hazard ratio [HR] 0.61; 95% confidence interval [95%CI] 0.50,0.74; p < 0.001) and DFS (HR 0.61; 95%CI 0.57,0.65; p < 0.001) compared to BMM-negative patients. In multivariable analyses, the presence of BMM remained an independent prognostic factor for OS and DFS (table). Conclusions: The presence of BMM is a frequent phenomenon occurring in over one third of stage I-III colon cancer patients. The present prospective cohort study provides compelling evidence that BMM represent a significant, independent prognostic factor for DFS and OS in colon cancer patients even with long-term follow-up. The use of adjuvant chemotherapy in node negative patients with BMM may be justified. Clinical trial information: NCT00826579.Multivariable analysis. OS DFS HR (95%CI) p-value HR (95%CI) p-value BM negative vs positive 0.69 (0.59, 0.80) <0.001 0.69 (0.65, 0.72) <0.001 Age (per 10 years increase) 2.02 (1.73, 2.35) < 0.001 1.73 (1.58, 1.89) < 0.001 Male vs female 1.16 (0.79, 1.71) 0.440 1.33 (1.01, 1.75) 0.044 T stage (T1/2 vs T3/4) 1.34 (0.55, 3.28) 0.519 1.18 (0.57, 2.41) 0.658 Nodal status (N0 vs N+) 0.48 (0.39, 0.59) < 0.001 0.52 (0.42, 0.66) < 0.001