Tamoxifen and its main metabolites serum and tissue concentrations in breast cancer women

Mario Furlanut, Loretta Franceschi, Enrico Pasqual, Stefano Bacchetti, Donatella Poz, Giorgio Giorda, Pierpaolo Cagol

Research output: Contribution to journalArticlepeer-review


Because of a possible relationship between tamoxifen (T) concentrations and clinical effects, we initiated a preliminary investigation on serum and tissue concentrations of T and its main active metabolites, and 4-hydroxytamoxifen, in women with positive breast cancer estrogen receptor. One hundred forty-eight patients were studied: 80 were admitted for monitoring of therapeutic serum drug concentrations, 22 had tissue concentrations taken at surgery, and 46 patients had uterine mucosa levels measured at diagnostic hysteroscopy. Steady-state serum concentrations were reached after 1 month of continuous treatment, with desmethyltamoxifen being the highest represented derivative from the third week onward. There was no relationship between dose (in mg/kg body weight) and steady-state serum concentrations during therapeutic drug monitoring of patients. The highest tissue concentrations were observed in breast lymph-nodes, cancer tissue, and uterine mucosa. On the basis of these data, we speculate that T and its active metabolites may exert both a defensive role (ie, an obstacle to the diffusion of malignant cells through the local lymphatic system) and a harmful one (induction of uterine malignancies).

Original languageEnglish
Pages (from-to)349-352
Number of pages4
JournalTherapeutic Drug Monitoring
Issue number3
Publication statusPublished - Jun 2007


  • Active metabolites
  • Breast cancer
  • Tamoxifen
  • Tissue concentrations

ASJC Scopus subject areas

  • Toxicology
  • Health, Toxicology and Mutagenesis
  • Pharmacology
  • Biochemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology (medical)
  • Public Health, Environmental and Occupational Health


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