- One in six premenopausal women (16%) showed inadequate adherence to tamoxifen after one year.
- 10.7% had undetectable serum levels, indicating complete nonadherence.
- Self-declaration is not a reliable indicator of adherence.
- Doctors should ask about side effects, encourage openness about nonadherence, and work with patients on strategies to help them adhere.
Why this matters
Nonadherence to long-term hormonal therapy (ie, taking
- 16.0% (188/1177) of premenopausal women prescribed tamoxifen in the CANTO trial showed inadequate adherence at one year (based on serum assessment of tamoxifen
- Within this group, 10.7% of the total population under study had undetectable levels of tamoxifen and were classed as nonadherent.
- Half of those with inadequate adherence had self-declared as adherent.
- CANTO COMPLETE was a pre-defined substudy of CANTO, a French prospective longitudinal study of 12,000 patients with recently diagnosed stage I-III breast cancer. The objective of CANTO is to characterize the long-term impact of treatment toxicities.
- CANTO COMPLETE examined the prevalence and predictors of nonadherence to hormone therapy in premenopausal women, using serum assessment of drug levels and matching them with patients’ self-declaration of adherence.
Serum tamoxifen was measured at only one time point, reflecting levels over the previous month only.
“Non-compliance with adjuvant hormonal treatment is an under-appreciated and under-reported problem and places patients at risk of inadequate clinical benefit,” said ESMO’s invited commentator, Giuseppe Curigliano, University of Milan, Italy.