Adherence to adjuvant tamoxifen and associated factors in breast cancer survivors.

Purpose: Adjuvant endocrine therapy reduces the recurrence and mortality of early hormone receptor-positive breast cancer in both pre- and postmenopausal women. The aim of this study was to investigate adjuvant tamoxifen adherence and associated factors in breast cancer survivors.

Methods: This descriptive, prospective study was conducted in 2019-2020 with the participation of 531 women who survived breast cancer and were under follow-up at the Senology Institute of a hospital in Istanbul. Inclusion criteria were having completed treatment for early hormone receptor-positive breast cancer, being prescribed tamoxifen, and being 18 years or older. Data were collected using a patient information form and the Morisky Medication Adherence Scale-8 (MMAS-8).

Results: The mean age of the participants was 44.9 ± 6.5 years, and the mean duration of tamoxifen use was 834.4 ± 685.7 days. The women's mean MMAS-8 score was 6.86 ± 1.39. Medication adherence was significantly positively correlated with current age (p = 0.006) and age at diagnosis (p = 0.002). There was a statistically significant difference between tamoxifen adherence according to participants' employment status (p = 0.028), chronic disease status (p = 0.018), loss of libido (p = 0.012), treatment-related changes in mood changes (p = 0.004), and having negative effects affecting daily life (p < 0.001).

Conclusion: Overall, breast cancer survivors in this study reported moderate adherence to tamoxifen. The women's individual characteristics and the adverse effects of treatment influenced medication adherence. Healthcare professionals can help increase adherence to this treatment, which reduces the risk of mortality, by explaining the importance of the medication, identifying and eliminating barriers to adherence, and informing women about evidence-based interventions to increase medication compliance.