TAM causes several side effects that impact the quality of life and adherence to treatment in patients with BC. Due to the complexity of TAM metabolism, serum biomarkers predicting TAM side effects have not been identified. We hypothesized that TAM levels may be associated with side effects, thus identifying pts eligible to tailored supportive interventions.
CANTO cohort (NCT01993498) is a French multicenter prospective longitudinal study including 12000 women with stage I-III BC aimed at characterizing long-term toxicities of BC treatment. CANTO COMPLETE is a pre-defined sub study of adherence to endocrine therapy evaluating TAM serum concentrations in premenopausal pts. Here, we analyzed the association between continuous TAM serum levels and side effects at 1 year of TAM initiation in pts with serum defined adherence to TAM (> 60 ng/mL). TAM level was determined by liquid chromatography tandem mass spectrometry on 200 µL of serum. Selected TAM-related toxicities were assessed by increase in body weight ≥5%, CTCAE v4.0 and patient reported outcomes (EORTC C30 and hospital anxiety and depression scale [HADS]). Univariate and multivariate linear and logistic regressions were fitted to measure the association between TAM levels and selected toxicities.
A cohort of 989 pts with serum defined adherence to TAM was identified. Median age at diagnosis was 45 yrs (min.-max. 22 - 57), 43.7% were stage I, 64.6% received (neo)adjuvant chemotherapy, 89.4% had Charlson score 0, 33.8% had BMI≥25 kg/m2, 20.9% were active smokers and 52.4% had education ≥ college. Median serum TAM was 119 ng/ml (P25-P75 96-152). In univariate and multivariate analyses, TAM levels were not associated with worse side effects, in specific: weight gain; gynecological, musculoskeletal or neurologic toxicities (including cognitive); fatigue or insomnia; and anxiety or depression.
In premenopausal women adherent to adjuvant TAM, TAM serum levels were not associated with TAM-related side effects at 1 year post treatment initiation. As next steps, we will analyze the association of tamoxifen metabolites and side effects.
NCT01993498.
INSERM UMR 981.
Institut National du Cancer (to Fabrice André and Barbara Pistilli), Susan G. Komen (to Ines Vaz-Luis) and Fondation ARC (to Ines Vaz-Luis and Gwenn Menvielle).
All authors have declared no conflicts of interest.