Prospective studies based on the storage of biological samples at low temperature have opened new perspectives in etiological research on cancer. In planning these studies a crucial question is to evaluate whether the long- term preservation of the samples is able to affect the categorization of the subjects involved. In the frame of the ORDET project, a prospective study of hormones and diet in the etiology of breast cancer provided with a -80°C biological bank, we have evaluated the stability of estradiol, free and total testosterone, progesterone, and prolactin in serum and plasma samples over 3 years of cryoconservation. Study results showed that the subjects maintained almost the same rank by hormonal concentration throughout the 3-year period for all hormones. Looking at the stability over time, estradiol, prolactin, and total testosterone had fairly good performance for both serum and plasma. Serum-free testosterone increased in time up to 30%, whereas progesterone decreased by about 4.0% of the initial concentration. However, the reliability of the individual categorization by hormonal level suggests the validity of low temperature storage for epidemiological purposes, at least for hormonal parameters.
|Number of pages||5|
|Journal||Cancer Epidemiology Biomarkers and Prevention|
|Publication status||Published - 1995|
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