The aim of this study was to identify K-ras mutations as marker for isolated tumor cells in liver, lymph node, and bone marrow specimens of colorectal cancer patients. To detect these, a PCR-RFLP assay was used with a sensitivity exceeding that of routine histopathology by at least 1 order of magnitude. In addition, the ratio of mutated versus wildtype alleles was determined by an internal standard. Of 199 patients, 74 (37.5%) were found to bear a K-ras-positive tumor. Of these, 60 (81%) were mutated in codon 12 and 14 (19%) in codon 13 (P < 0.001). In addition, 14 organs were found K-ras positive, 13 of which were from 12 patients with a K-ras-positive tumor (16%) and 1 from a patient with a K-ras-negative tumor (0.8%). Eight patients exhibited liver involvement and 6 showed lymph node involvement. Remarkably, no bone marrow specimen was found K-ras positive (P < 0.017 versus liver involvement). Sequence analysis of tumor DNA revealed that GGT (Gly) was replaced by GAT (Asp; 35%), GTT (Val; 32%), AGT (Ser; 13%), GCT (Ala; 10%), TGT (Cys; 8%), and CGT (Arg; 2%) for codon 12, and by GAC (Asp) as the only type of mutation for codon 13. In colorectal carcinomas the ratio of K-ras mutated versus wild-type alleles ranged over 4 orders of magnitude (10 0 -10 ؊4 , median: 10 ؊2 ) and was correlated with both, residual tumor load (R1/2; P ‫؍‬ 0.028) and distant metastasis (M1; P ‫؍‬ 0.057). These results show that detection of K-ras mutated alleles by PCR-RFLP in patients with colorectal carcinoma may aid in the identification of isolated tumor cells. High ratios of K-ras alleles were correlated with certain negative prognostic parameters (R,M). In accord with its function as a primary filter for colorectal carcinoma cells, the liver was more often contaminated with K-ras-positive cells than bone marrow.

The aim of our prospective study was to detect circulating epithelial cells (CEC) indicating the presence of disseminated tumor cells (DTC) in tissues affected by lymphatic and hematogenic colorectal cancer metastasis. DTC were tracked in lymph node, liver or bone marrow samples of 245 colorectal cancer patients using 2 independent RT-PCR assays for cytokeratin 20 (CK20) and guanylylcyclase C (GCC) that demonstrated a sensitivity of 1 colorectal cancer cell in 10 6 nucleated hematopoietic cells. CK20 mRNA was detected in 79% of lymph nodes, 35% of both liver lobes and 11% of bone marrow samples. GCC mRNA was found in 68% of lymph nodes, 60% of both liver lobes and 6% of bone marrow specimens. Both markers were recorded in 63% of lymph nodes, 45% of at least 1 liver lobe and 1% of bone marrow samples. There was no significant difference when comparing lymph node samples tested positive for both markers in patients with (N1/2; 65%) and without (N0; 56%) nodal involvement. The same was true when comparing the percentages of patients with and without clinically overt distant metastasis who were positive for both markers in at least 1 liver lobe (62% vs. 41%) or in bone marrow (4% vs. 0%). A score denoting the cumulative sum of tests indicating presence of CK20 and GCC mRNA in the liver was significantly related with UICC classification (p ‫؍‬ 0.039). However, addition of lymph node results to this score decreased the correlation. The high incidence of clinically inconspicuous lymph node and liver samples tested positive for both markers emphasizes the function of these organs as primary filters for epithelial cells possibly shed from colorectal carcinomas. The potential prognostic significance of these findings warrants verification, especially regarding the importance of CEC or DTC resident in the liver of colorectal cancer patients.

Background: Tripe palms is a descriptive term for a cutaneous paraneoplastic keratoderma. Tripe palms are frequently associated with gastric and pulmonary carcinoma. The pathogenetic mechanism remains unknown. Objective: To determine the influence of receptor tyrosine kinases, which are both expressed in pulmonary carcinomas and in human skin, we performed expression studies on epidermal growth factor receptor (EGFR), HER2, HER3 in a skin sample of tripe palms obtained from a patient with non-small-cell lung cancer with lymph node involvement. Two months after diagnosis, the patient had developed palmoplantar ‘tripe palms’. Additionally, the expression of SRC, c-myc and p16/ CDKN2 were studied. Method: Conventional reverse-transcription polymerase chain reaction was performed on a tissue sample of tripe palms. Results: Weak expression of HER2 and of p16/CDKN2 was found. EGFR, HER3, c-myc and SRC were not expressed. Conclusion: Receptor tyrosine kinases of subclass I, the tyrosine kinase SRC and the oncogene c-myc play no major role in the pathogenesis of this case of tripe palms.