Early discontinuation of tamoxifen intake in younger women with breast cancer: is it time to rethink the way it is prescribed?

BACKGROUND: Tamoxifen is the main recommended adjuvant hormonal treatment for premenopausal women with hormone-responsive early breast cancer. Little data is available on compliance and persistence to tamoxifen intake in younger women.
METHODS: Using the French National Health Insurance System database, we constituted a cohort of 288 women who were diagnosed with breast cancer and received at least one supply of tamoxifen for breast cancer between September 2005 and July 2011. Medical records and mailed questionnaires provided complementary sources of data. Time to treatment discontinuation and associated predictors were studied using techniques for censored data.
RESULTS: Among women who received a prescription of tamoxifen, 6.1% (16) did not fill any prescription. After 2 years of tamoxifen intake, 29.7% (95%confidence interval (CI) 24.1-36.4) had discontinued their treatment; after 3 years this percentage increased to 39.5% (95% CI 32.9-47.0). The risk of treatment discontinuation rose sharply during the 1st year of treatment and remained approximately constant in the second year. After multivariate adjustment, tamoxifen discontinuation increased significantly with low social support (Hazard Ratio (HR) = 2.1; 95%CI 1.2-3.4), and self-reporting of non-compliance behaviour (HR = 2.2; 95% CI 1.3-3.7).
CONCLUSION: The consequences of high treatment discontinuation rates in younger women with long potential life expectancy may be significant. There is an urgent need to acknowledge and tackle compliance issues in the field of oncology, unless we are willing to accept inefficient prescriptions of efficacious drugs.