Low Z-4OHtam concentrations are associated with adverse clinical outcome among early stage premenopausal breast cancer patients treated with adjuvant tamoxifen

Low steady‐state levels of active tamoxifen metabolites have been associated with inferior treatment outcomes. In this retrospective analysis of 406 estrogen receptor‐positive breast cancer (BC) patients receiving adjuvant tamoxifen as initial treatment, we have associated our previously reported thresholds for the two active metabolites, Z‐endoxifen and Z‐4‐hydroxy‐tamoxifen (Z‐4OHtam), with treatment outcomes in an independent cohort of BC patients. Among all patients, metabolite levels did not affect survival. However, in the premenopausal subgroup receiving tamoxifen alone (n = 191) we confirmed an inferior BC ‐specific survival in patients with the previously described serum concentration threshold of Z‐4OHtam ≤ 3.26 nm (HR = 2.37, 95% CI = 1.02–5.48, P = 0.039). The ‘dose–response’ survival trend in patients categorized to ordinal concentration cut‐points of Z‐4OHtamoxifen (≤ 3.26, 3.27–8.13, > 8.13 nm) was also replicated (P‐trend log‐rank = 0.048). Z‐endoxifen was not associated with outcome. This is the first study to confirm the association between a published active tamoxifen metabolite threshold and BC outcome in an independent patient cohort. Premenopausal patients receiving 5‐year of tamoxifen alone may benefit from therapeutic drug monitoring to ensure tamoxifen effectiveness.publishedVersio

Low Z-4OHtam concentrations are associated with adverse clinical outcome among early stage premenopausal breast cancer patients treated with adjuvant tamoxifen

Abstract Low steady‐state levels of active tamoxifen metabolites have been associated with inferior treatment outcomes. In this retrospective analysis of 406 estrogen receptor‐positive breast cancer (BC) patients receiving adjuvant tamoxifen as initial treatment, we have associated our previously reported thresholds for the two active metabolites, Z‐endoxifen and Z‐4‐hydroxy‐tamoxifen (Z‐4OHtam), with treatment outcomes in an independent cohort of BC patients. Among all patients, metabolite levels did not affect survival. However, in the premenopausal subgroup receiving tamoxifen alone (n = 191) we confirmed an inferior BC ‐specific survival in patients with the previously described serum concentration threshold of Z‐4OHtam ≤ 3.26 nm (HR = 2.37, 95% CI = 1.02–5.48, P = 0.039). The ‘dose–response’ survival trend in patients categorized to ordinal concentration cut‐points of Z‐4OHtamoxifen (≤ 3.26, 3.27–8.13, > 8.13 nm) was also replicated (P‐trend log‐rank = 0.048). Z‐endoxifen was not associated with outcome. This is the first study to confirm the association between a published active tamoxifen metabolite threshold and BC outcome in an independent patient cohort. Premenopausal patients receiving 5‐year of tamoxifen alone may benefit from therapeutic drug monitoring to ensure tamoxifen effectiveness

Low Z-4OHtam concentrations are associated with adverse clinical outcome among early stage premenopausal breast cancer patients treated with adjuvant tamoxifen

Low steady‐state levels of active tamoxifen metabolites have been associated with inferior treatment outcomes. In this retrospective analysis of 406 estrogen receptor‐positive breast cancer (BC) patients receiving adjuvant tamoxifen as initial treatment, we have associated our previously reported thresholds for the two active metabolites, Z‐endoxifen and Z‐4‐hydroxy‐tamoxifen (Z‐4OHtam), with treatment outcomes in an independent cohort of BC patients. Among all patients, metabolite levels did not affect survival. However, in the premenopausal subgroup receiving tamoxifen alone (n = 191) we confirmed an inferior BC ‐specific survival in patients with the previously described serum concentration threshold of Z‐4OHtam ≤ 3.26 nm (HR = 2.37, 95% CI = 1.02–5.48, P = 0.039). The ‘dose–response’ survival trend in patients categorized to ordinal concentration cut‐points of Z‐4OHtamoxifen (≤ 3.26, 3.27–8.13, > 8.13 nm) was also replicated (P‐trend log‐rank = 0.048). Z‐endoxifen was not associated with outcome. This is the first study to confirm the association between a published active tamoxifen metabolite threshold and BC outcome in an independent patient cohort. Premenopausal patients receiving 5‐year of tamoxifen alone may benefit from therapeutic drug monitoring to ensure tamoxifen effectiveness

Who are the women who enrolled in the POSITIVE trial: A global study to support young hormone receptor positive breast cancer survivors desiring pregnancy

Background: Premenopausal women with early hormone-receptor positive (HR+) breast cancer receive 5–10 years of adjuvant endocrine therapy (ET) during which pregnancy is contraindicated and fertility may wane. The POSITIVE study investigates the impact of temporary ET interruption to allow pregnancy. Methods: POSITIVE enrolled women with stage I-III HR + early breast cancer, ≤42 years, who had received 18–30 months of adjuvant ET and wished to interrupt ET for pregnancy. Treatment interruption for up to 2 years was permitted to allow pregnancy, delivery and breastfeeding, followed by ET resumption to complete the planned duration. Findings: From 12/2014 to 12/2019, 518 women were enrolled at 116 institutions/20 countries/4 continents. At enrolment, the median age was 37 years and 74.9 % were nulliparous. Fertility preservation was used by 51.5 % of women. 93.2 % of patients had stage I/II disease, 66.0 % were node-negative, 54.7 % had breast conserving surgery, 61.9 % had received neo/adjuvant chemotherapy. Tamoxifen alone was the most prescribed ET (41.8 %), followed by tamoxifen + ovarian function suppression (OFS) (35.4 %). A greater proportion of North American women were <35 years at enrolment (42.7 %), had mastectomy (59.0 %) and received tamoxifen alone (59.8 %). More Asian women were nulliparous (81.0 %), had node-negative disease (76.2%) and received tamoxifen + OFS (56.0 %). More European women had received chemotherapy (69.3 %). Interpretation: The characteristics of participants in the POSITIVE study provide insights to which patients and doctors considered it acceptable to interrupt ET to pursue pregnancy. Similarities and variations from a regional, sociodemographic, disease and treatment standpoint suggest specific sociocultural attitudes across the world