Microsatellite instability did not predict individual survival of unselected patients with colorectal cancer.

INTRODUCTION: High microsatellite instability (MSI-H) occurs in about 15% of colorectal cancers (CRC) and clinical as well as pathological features differ from tumours exhibiting low microsatellite instability (MSI-L) or microsatellite stability (MSS). Conflicting data exists about the relevance of MSI in predicting the prognosis and benefit of 5-fluorouracil (5-FU) based chemotherapy in patients with CRC. We investigated the usefulness of MSI as a predictor of distinct clinical attributes influencing recurrence rate and disease-free survival (DFS) subject to the use of adjuvant or palliative chemotherapy with 5-FU in stage II- stage IV CRC. METHODS: We collected data and tumours of 416 consecutive stage I to IV CRC patients from 2000 to 2002, and followed them for a median time of 33 months. Microsatellite loci recommended by the National Cancer Institute were analysed. Cox proportional hazard modelling was used to compare clinical data and survival as well as associations for MSI and 5-FU treatment status of patients with MSI-H, MSI-L or MSS CRC. RESULTS: We identified 52 MSI-H (13%), 21 MSI-L (5%) and 343 MSS (82%) tumours. CRC with MSI-H tended to have a decreased likelihood of metastasising to regional lymph nodes (p=0.055), whilst age of diagnosis and tumour location did not differ. In an analysis that did not take into account the use of chemotherapy, univariate and multivariate analyses failed to show a difference between MSI-H and MSS groups with respect to disease-free and overall survival. Furthermore, survival under application of 5-FU did not correlate with MSI status. CONCLUSION: No clear influence of MSI status on overall survival and response to 5-FU chemotherapy was found.

Frequency of hereditary non-polyposis colorectal cancer among unselected patients with colorectal cancer in Germany.

INTRODUCTION: Hereditary non-polyposis colorectal cancer (HNPCC) is a major form of familial colorectal cancer (CRC). It is diagnosed when either the Amsterdam criteria (AC) are fulfilled or mutations in one of the mismatch repair (MMR) genes have been identified. This project aims at estimating the proportion of HNPCC among unselected patients with CRC. PATIENTS AND METHODS: During a period of 2 years, a total of 351 non-selected patients with CRC were registered prospectively. 92 patients met the Bethesda criteria (9 of them fulfilled the AC) and 259 did not. 348 tumours were examined for microsatellite instability (MSI) and expression of MMR proteins. RESULTS: MSI-H and MSI-L were identified in 17 and 6%, respectively. Loss of MSH2 or MLH1 was found in 1.5 and 8.8%, respectively. Based on the results of tumour tissue analyses, 80 patients with MSI and/or loss of MSH2 or MLH1 expression were identified as candidates for germline mutation screening. DNA of 40/80 patients was available. These patients were screened for MSH2 and MLH1 mutations; 19/40 patients with MSI and normal MSH2 or MLH1 expression were screened for mutations in MSH6. Three patients had relevant MMR gene mutations and six variants of unknown functional relevance were detected. CONCLUSIONS: After adjusting for the cases not evaluable for germline mutations, 1.7% of the CRC patients had HNPCC proven by molecular genetics.

The p53 codon 72 variation is associated with the age of onset of hereditary non-polyposis colorectal cancer (HNPCC).

The polymorphic variants at codon 72 of the p53 gene were shown to be functionally distinct in vitro, whereby the arginine (arg) variant induces apoptosis more efficiently than the proline (pro) variant. From the evidence that the DNA mismatch repair system and p53 interact to maintain genomic integrity, we hypothesized that the codon 72 variation may influence the age of onset of disease in HNPCC patients. We tested 538 patients for p53 codon 72 variants, including 167 unrelated patients with pathogenic germline mutations in MSH2 or MLH1 and colorectal carcinoma as first tumour, 126 patients with sporadic microsatellite stable colorectal cancers, and 245 healthy controls. The median age of onset was 41, 36, and 32 years for MSH2 or MLH1 mutation carriers with arg/arg, arg/pro, and pro/pro genotypes, respectively. The log rank test revealed significant differences in the age of onset between arg/arg and pro/pro individuals (p = 0.0002) and in arg/pro versus arg/arg and pro/pro individuals (p = 0.0026 and p = 0.0217, respectively). A Cox regression model indicated an additive mode of inheritance. No significant differences in age of onset were observed among different genotype carriers with microsatellite stable tumours. Our results suggest that p53 codon 72 genotypes are associated with the age of onset of colorectal carcinoma in a mismatch repair deficient background in a dose dependent manner. These findings may be relevant for preventive strategies in HNPCC.

Cirrhotic patients with or without hepatocellular carcinoma harbour AFP-specific T-lymphocytes that can be activated in vitro by human alpha-fetoprotein.

BACKGROUND: Alpha-fetoprotein (AFP) is re-expressed in 60%-70% of hepatocellular carcinomas (HCC) and may therefore be a potential target for a prophylactic or therapeutic tumour-specific vaccination. A prerequisite for this approach is the possibility to induce AFP-specific T-lymphocytes in patients with HCC and/or cirrhosis. METHODS: Peripheral blood was examined for the presence of AFP-specific T-lymphocytes using a FACS-based interferon-gamma secretion assay. RESULTS: In a group of healthy volunteers, the presence of AFP-specific CD4- and CD8-lymphocytes was demonstrated. Screening of blood of 14 cirrhotic patients without HCC and 23 cirrhotic patients with HCC showed that patients with liver diseases that represent targets for vaccination also harbour CD4-positive as well as CD8-positive AFP-specific Tlymphocytes. AFP reactivity in patients' lymphocytes was not significantly influenced by soluble serum AFP. The median stimulation factors for CD4-positive T-lymphocytes were significantly higher (P = 0.0365) in cirrhotic patients without HCC (median 2.08, range 0.50-4.40) compared to cirrhotic patients with HCC (median 1.15, range 0.24-8.50). CONCLUSION: AFP-specific T-lymphocytes that may be instrumental in HCC vaccination strategies are present in humans. This study suggests that immunopreventive vaccination of cirrhotic patients rather than immunotherapeutic vaccination of HCC patients may be preferable.