Erythrocyte alpha-tocopherol in breast cancer patients treated with letrozol.

In an earlier study, we have observed an increase of alpha-tocopherol in breast cancer patients treated with third-generation aromatase inhibitors that was related to tamoxifen withdrawal. We report here the results of measurement of alpha-tocopherol in erythrocytes and alpha-tocopherol/cholesterol ratios in patients treated with letrozol. Alpha-tocopherol in lipoprotein fractions and erythrocytes was determined by high-performance liquid chromatography in 124 post-menopausal women with breast cancer treated with letrozol immediately before the start of treatment as well as 2 and 4 mo later. After a transient decrease after 2 mo of letrozol therapy, erythrocyte alpha-tocopherol concentrations returned to pre-treatment levels 4 mo after the start of treatment. Apart from lower cholesterol in patients pre-treated with tamoxifen, no significant differences were observed at baseline between patients previously treated with tamoxifen and patients who had no prior tamoxifen in any of the other parameters investigated, but the transient decrease of erythrocyte alpha-tocopherol was observed only in patients previously treated with tamoxifen. Alpha-tocopherol content of lipoprotein fractions was significantly increased 4 mo after the start of therapy, but this increase was evident mostly in patients not treated earlier with tamoxifen. In conclusion, only minor changes of alpha-tocopherol, including a transient decrease of alpha-tocopherol in erythrocyte membranes, and an increase of alpha-tocopherol in lipoprotein fractions were observed during the first 4 mo of letrozol therapy.