BMC Cancer 2006, 6:10 http://www.biomedcentral.com/1471-2407/6/10 pathways in the regulation of Ck 8/18 are conceivably Authors' contributions existing. TF: Project planning, data analysis and writing of the man- In general, cytokeratin expression patterns are highly-con- served. The above mentioned data from the literature showed that any change in the intermediate filament expression pattern reflects or underlies changes in sub- stantial cellular properties. Strong homologies could also be shown in other carcinomas. In primary breast cancer, this could be demonstrated with different approaches. Down-regulated expression of cytokeratin Ck 8/18 was associated with increased metastatic properties and poor prognosis in breast cancer [30]. The expression of Ck 5 in a small subset of invasive breast cancers was in contrast associated with a poor prognosis [31]. Interestingly, the expression of vimentin, alone or in com- bination with Ck 8/18 and 19, was not associated with poor prognosis or higher tumour stages. A multitude of studies gave evidence that the expression of vimentin in carcinomas has to be interpreted as a sign of an epithelial- mesenchymal transition, associated with high tumour aggressiveness [9,32]. This association remains questiona- ble, since the expression of vimentin has already been described in non-invasive premalignant lesions of squa- mous epithelium and cultured keratinocytes. Finally, from a clinical point of view, our results show that the determination of the Cytokeratin 8–18 and 19-expres- sion in SCC of the oral cavity harbours a significant prog- nostic potential. Our results seem to define subgroups of high-risk patients who might benefit from more intensive therapy or new therapeutic strategies like Cytokeratin 19 antibodies [33]. For human ovarian adenocarcinoma cells it could be shown that cytokeratins 18 could sensitize these cells to cisplatin [34]. These results demonstrate that modulating the expression of an intermediate filament protein results in sensitization to chemotherapeutic drugs. The subgroup of ck 8–18 positive squamous cell carcinoma may have a benefit by chemotherapy with cis- platin. Further investigations are necessary to determine the clinical impact of these hypotheses. Conclusion In conclusion, our results in a series of 308 primary, pre- viously untreated SCC's of the oral cavity showed an important prognostic impact for the expression of glandu- lar, simple cytokeratins in SCC's. Further studies have to unravel the underlying regulatory changes in order to allow the definition of specific therapies of these high risk cancer patients. 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