In Response: We thank Dr. Jung for the special interest in our work regarding the tissue and serum levels of tissue inhibitor of metalloproteinase 1 (TIMP-1) as prognostic markers in head and neck squamous cell carcinoma (1).
We have shown in our study that high preoperative serum TIMP-1 levels as well as high expression of TIMP-1 in tumor tissue were linked with poor cause-specific as well as poor relapse-free survival in head and neck squamous cell carcinoma (HNSCC) patients (1). In our study, the median serum level for TIMP-1 immunoreactive protein of HNSCC patients was 527 ng/ml, mean 565 ng/ml. Additionally, the level of the TIMP-1 in 44 healthy controls was lower, median 409 ng/ml, mean 432 ng/ml (P < 0.001). The level of the serum TIMP-1 was very high in the report mentioned by Dr. Jung in his letter and also in previous report by Jung et al. (2). In our study, the TIMP-1 levels in controls equal the plasma levels of ten healthy volunteers in report by Jung (3). In collecting the serum samples, Jung had used serum tubes with additives (kaolin-coated). In our study, the serum samples were all so-called native serum samples, (i.e. collected with tubes with no additives). We also want to point out that in our study all samples were prospective and have been handled in a consistent method.
In conclusion, we appreciate the comments by Dr. Jung and we greatly agree that when estimating the circulating TIMP-1, the interpretation of the results should include a certain reservation, unless the methodological aspects are taken account.
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