Colon cancer is a major contributor to can- cer-related mortality worldwide. Death from colon cancer occurs in the majority of cases from widespread metastatic disease. Only 15% of stage II colon... Show moreColon cancer is a major contributor to can- cer-related mortality worldwide. Death from colon cancer occurs in the majority of cases from widespread metastatic disease. Only 15% of stage II colon cancer patients that develop metastasis will benefit from adjuvant chemotherapy, all of them will suffer from treatment-related toxicity. This makes it essential for the clinician to precisely identify the patient cohort at risk for metastasis. Prognostic biomarkers might improve current staging criteria. In this thesis a tumor biology-directed approach is applied to study and develop bio- markers focusing on tumor proliferation and evasion of apoptosis and immune destruction Show less
BACKGROUND The intra-tumor stroma percentage in colon cancer (CC) patients has previously been reported by our group as a strong independent prognostic parameter. Patients with a high stroma... Show moreBACKGROUND The intra-tumor stroma percentage in colon cancer (CC) patients has previously been reported by our group as a strong independent prognostic parameter. Patients with a high stroma percentage within the primary tumor have a poor prognosis. PATIENTS AND METHODS Tissue samples from the most invasive part of the primary tumor of 710 patients (52% Stage II, 48% Stage III) participating in the VICTOR trial were analyzed for their tumor-stroma percentage. Stroma-high (>50%) and stroma-low (≤50%) groups were evaluated with respect to survival times. RESULTS Overall and disease-free survival times (OS and DFS) were significantly lower in the stroma-high group (OS P<0.0001, hazard ratio (HR)=1.96; DFS P<0.0001, HR=2.15). The 5-year OS was 69.0% versus 83.4% and DFS 58.6% versus 77.3% for stroma-high versus stroma-low patients. CONCLUSION This study confirms the intra-tumor stroma ratio as a prognostic factor. This parameter could be a valuable and low cost addition to the TNM status and next to current high-risk parameters such as microsatellite instability status used in routine pathology reporting. When adding the stroma-parameter to the ASCO criteria, the rate of 'undertreated' patients dropped from 5.9% to 4.3%, the 'overtreated' increased with 6.8% but the correctly classified increased with an additional 14%. Show less
BACKGROUND There are no established biomarkers to identify tumour recurrence in stage II colon cancer. As shown previously, the enzymatic activity of the cyclin-dependent kinases 1 and 2 (CDK1 and... Show moreBACKGROUND There are no established biomarkers to identify tumour recurrence in stage II colon cancer. As shown previously, the enzymatic activity of the cyclin-dependent kinases 1 and 2 (CDK1 and CDK2) predicts outcome in breast cancer. Therefore, we investigated whether CDK activity identifies tumour recurrence in colon cancer. METHODS In all, 254 patients with completely resected (R0) UICC stage II colon cancer were analysed retrospectively from two independent cohorts from Munich (Germany) and Leiden (Netherlands). None of the patients received adjuvant treatment. Development of distant metastasis was observed in 27 patients (median follow-up: 86 months). Protein expression and activity of CDKs were measured on fresh-frozen tumour samples. RESULTS Specific activity (SA) of CDK1 (CDK1SA), but not CDK2, significantly predicted distant metastasis (concordance index=0.69, 95% confidence interval (CI): 0.55-0.79, P=0.036). Cutoff derivation by maximum log-rank statistics yielded a threshold of CDK1SA at 11 (SA units, P=0.029). Accordingly, 59% of patients were classified as high-risk (CDK1SA ≥11). Cox proportional hazard analysis revealed CDK1SA as independent prognostic variable (hazard ratio=6.2, 95% CI: 1.44-26.9, P=0.012). Moreover, CKD1SA was significantly elevated in microsatellite-stable tumours. CONCLUSION Specific activity of CDK1 is a promising biomarker for metastasis risk in stage II colon cancer. Show less
