A nested case-control study of adjuvant hormonal therapy persistence and compliance, and early breast cancer recurrence in women with stage I-III breast cancer

Background: Non-persistence and non-compliance are common in women prescribed hormonal therapy for breast cancer, but little is known about their influence on recurrence. Methods: A nested case-control study of associations between hormonal therapy non-persistence and non-compliance and the risk of early recurrence in women with stage I-III breast cancer was undertaken. Cases, defined as women with a breast cancer recurrence within 4 years of hormonal therapy initiation, were matched to controls (1 : 5) by tumour stage and age. Conditional logistic regression was used to examine associations between early recurrence and hormonal therapy non-persistence and noncompliance. Results: Ninety-four women with breast cancer recurrence were matched to 458 controls. Women who were non-persistent (>= 180 days without hormonal therapy) had a significantly increased adjusted recurrence odds ratio (OR) of 2.88 (95% CI 1.11, 7.46) compared with persistent women. There was no significant association between low compliance (OR 1.30; 95% CI 0.74, 2.30) and breast cancer recurrence. Conclusion: Hormonal therapy non-persistence is associated with a significantly higher risk of early recurrence in women with stage I-III oestrogen receptor (ER)-positive breast cancer. This finding is consistent with results from randomized studies of hormonal therapy treatment duration and suggests that interventions to target modifiable risk factors for non-persistence are required.