Serum Detection of Nonadherence to Adjuvant Tamoxifen and Breast Cancer Recurrence Risk

Study (n=1,177) reports therapeutic drug monitoring may be useful to promptly identify patients who do not take adjuvant tamoxifen as prescribed and are at risk for poorer outcomes (of 188 patients who did not adhere to tamoxifen prescription, 55% self-reported adherence).

SPS commentary:

After a median follow-up of 24.2 months since tamoxifen serum assessment, patients who were biochemically nonadherent had significantly shorter distant disease-free survival (adjusted hazard ratio, 2.31; 95% CI, 1.05 to 5.06; p=0.036), with 89.5% of patients alive without distant recurrence at 3 years in the nonadherent cohort versus 95.4% in the adherent cohort.

Journal of Clinical Oncology