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Analytical and clinical evaluation of CYFRA 21-1 by electrochemiluminescent immunoassay in head and neck squamous cell carcinoma: Author’s reply

noassay (ECLIA) for Cyfra 21-1 measurements in the serum of patients with squamous cell carcinomas of the head and neck. The advantages, or maybe also disadvantages, of the new ECLIA in contrast to the well accepted ELISA for determination of the Cyfra 21-1 serum concentration are not discussed by the authors, apart from the remark that the sensitivity of ECLIA seems to be slightly higher. ELISA is a rapid, sensitive, and reproducable technique, as well. Since with ECLIA a new technique is described, more detailed information concerning the performance of the test would be appropriate. As mentioned previously, no survival analysis should be performed with patients suffering from squamous cell carcinomas of different tumour sites in the head and neck area, because the survival probability per se strongly depends on the tumour site. This might explain the lack of statistical signicance in the difference between the Cyfra 211 positive and the Cyfra 21-1 negative group, described by Deng et al. In conformity with Deng et al., an increase of the Cyfra 21-1 serum concentration in case of disease progression, in terms of residual tumour progression, recurrency, and especially in terms of appearance of distant metastasis has previously been described. Also, a decrease of the Cyfra 21-1-serum concentration after therapy in patients with squamous cell carcinomas of the head and neck has been seen earlier. Cyfra 21-1 is a well accepted tumour marker in non-small-cell lung cancer. The controversy about the usefulness of Cyfra 21-1 as serum tumour marker in head and neck squamous cell carcinomas is probably due to difculties to nd the appropriate cut-off level. Cyfra 21-1 serum levels in patients with head and neck cancer are generally lower than in patients with lung cancer and they are often even equivalent to levels which are considered normal in lung cancer patients. Additionally, a wide range of Cyfra 21-1 serum levels were observed in patients at the time of primary tumour diagnosis. Also, the Cyfra 21-1 serum levels vary widely in healthy persons. Cytokeratins are not organ specic, and they appear in all epithelial tumours, as well as in normal epithelium. This is a limitation on the tumour marker potential of Cyfra 21-1. In conclusion, the Cyfra 21-1 serum concentration is not a suitable tumour marker for diagnosis of squamous cell carcinomas of the head and neck, but an increase of Cyfra 21-1 in serial measurements indicates impending disease progression in the individual patient. Therefore, the Cyfra 21-1 serum concentration is a good marker for follow-up in patients with squamous cell carcinoma of the head and neck, and in case of an upward trend of Cyfra 211 in the serum, staging procedures are recommended.