title: Validity for epidemiological studies of long-term cryoconservation of steroid and protein hormones in serum and plasma.
abstract: 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 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 degrees C biological bank, we have evaluated the stability of estradiol, free and total testosterone, 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 40% 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.
authors.affiliation: Consiglio Nazionale Ricerche, Instituto Citomorfologia Normale e Patologica, Sezione Bologna, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Bolelli
authors.forename: P
authors.initials: P
authors.lastname: Muti
authors.forename: A
authors.initials: A
authors.lastname: Micheli
authors.forename: R
authors.initials: R
authors.lastname: Sciajno
authors.forename: F
authors.initials: F
authors.lastname: Franceschetti
authors.forename: V
authors.initials: V
authors.lastname: Krogh
authors.forename: P
authors.initials: P
authors.lastname: Pisani
authors.forename: F
authors.initials: F
authors.lastname: Berrino
mesh_terms: D001793:Blood Preservation; D001943:Breast Neoplasms / Q000097:blood / Q000209:etiology; D015925:Cryopreservation; D004355:Drug Stability; D004958:Estradiol / Q000097:blood*; D005260:Female; D006801:Humans; D010949:Plasma / Q000737:chemistry*; D011374:Progesterone / Q000097:blood*; D011388:Prolactin / Q000097:blood*; D011446:Prospective Studies; D015203:Reproducibility of Results; D013739:Testosterone / Q000097:blood*; D013997:Time Factors
chemical_list: D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin