Genetic and epigenetic changes in primary metastatic and nonmetastatic colorectal cancer

Colorectal cancer (CRC) develops as multistep process, which involves genetic and epigenetic alterations. K-Ras, p53 and B-Raf mutations and RASSF1A, E-Cadherin and p16INK4A promoter methylation were investigated in 202 CRCs with and without lymph node and/or liver metastasis, to assess whether gene abnormalities are related to a metastogenic phenotype. K-Ras, B-Raf and p53 mutations were detected in 27, 3 and 32% of the cases, with K-Ras mutations significantly associated with metastatic tumour (P=0.019). RASSF1A, E-Cadherin and p16INK4A methylation was documented in 20, 44 and 33% of the cases with p16INK4A significantly associated with metastatic tumours (P=0.001). Overall, out of 202 tumours, 34 (17%) did not show any molecular change, 125 (62%) had one or two and 43 (21%) three or more. Primary but yet metastatic CRCs were prevalent in the latter group (P=0.023) where the most frequent combination was one genetic (K-Ras in particular) and two epigenetic alterations. In conclusion, this analysis provided to detect some molecular differences between primary metastatic and nonmetastatic CRCs, with K-Ras and p16INK4A statistically altered in metastatic tumours; particular gene combinations, such as coincidental K-Ras mutation with two methylated genes are associated to a metastogenic phenotype

CD3+ cells at the invasive margin of deeply invading (pT3-T4) colorectal cancer and risk of post-surgical metastasis : a longitudinal study

BACKGROUND: The density of tumour-infiltrating lymphocytes (TIL) has been proposed as an independent predictor of outcome in patients with colorectal cancer. However, the relative roles of TIL density, nodal status, and microsatellite instability (MSI) in predicting tumour progression to metachronous metastasis remain to be elucidated. The aim of this study was to assess the relationship between the density of CD3+ TIL and the postsurgical occurrence of distant-organ metastases in a large series of patients with deeply invading and MSI-typed colorectal cancer. METHODS: Per cent areas of immunoreactivity due to CD3+ TIL at the invasive margin of the tumour (CD3+ TIL(IM)) were measured by computer-assisted image analysis in 286 tissue specimens from pT3 or pT4 MSI-tested colorectal cancer. Tissue samples were taken from consecutive patients who underwent resection at the IRCCS Istituto Clinico Humanitas, Rozzano, Milan, Italy, from January, 1997, to November, 2004, for colorectal cancer with no evidence of metastasis at diagnosis. Occurrence of metachronous metastasis, disease-specific survival (DSS), and disease-free survival (DFS), were assessed retrospectively in relation to per cent immunoreactivity. FINDINGS: CD3+ TIL(IM) density was higher in MSI colorectal cancer than in mismatch repair-system-proficient tumours (6.53%vs 2.19%; p5%, 0.06, 0.01-0.48, p=0.008). Conversely, no significant association was seen between CD3+ immunoreactive area and risk of metachronous metastasis in node-positive colorectal cancer. Accordingly, CD3+ TIL(IM) density was associated with a better DSS (p=0.01) and DFS (p=0.006) only in patients with node-negative colorectal cancer. In primary tumours that had progressed to metachronous metastasis, stage III tumours had higher CD3+ TIL(IM) densities than stage II tumours (p=0.0004). INTERPRETATION: Metachronous metastases are unlikely to arise from node-negative colorectal cancers with a high-density CD3+ TIL(IM), whereas high densities of CD3+ TIL(IM) are not associated with the absence of postsurgical metastasis in patients with node-positive colorectal cancer. Our data suggest that densities of CD3+ TIL(IM) cannot be used as an independent predictor of clinical outcome in patients with stage III colorectal cancer and, at least for now, the tumour-node-metastasis classification should remain the preferred prognostic system. Our findings are consistent with a relationship between nodal involvement and tumour immunoevasion