Kensler KH, et al. – In this study, researchers investigated whether androgen receptor (AR) protein expression has value as a prognostic marker for breast cancer mortality. According to results, in the first 5-10 years postdiagnosis, there was an association of AR expression with improved prognosis in estrogen receptor (ER)-positive tumors, whereas, its association with worse prognosis was observed in ER-negative tumors. Overall, findings supported the continued evaluation of AR-targeted therapies for AR-positive/ER-negative breast cancers.

Methods

• Researchers used the Nurses’ Health Study (diagnosed 1976–2008) and Nurses’ Health Study II (1989–2008) cohorts to identify the 4,147 pre- and post-menopausal women with invasive breast cancer who were included in this study.
• They used immunohistochemistry to assess AR protein expression.
• AR protein expression was scored through pathologist review and as a digitally quantified continuous measure.
• They used Cox proportional hazards models, adjusting for patient, tumor, and treatment covariates, to estimate hazard ratios and 95% confidence intervals of breast cancer mortality.

Results

• A total of 806 breast cancer-related deaths were documented over a median 16.5 years of follow-up.
• Findings revealed an association of AR expression with a 27% reduction in breast cancer mortality overall, a 47% reduction for ER-positive cancers, and a 62% increase for ER-negative cancers, in the 7 years following diagnosis.
• Among ER-negative cancers, AR expression and breast cancer mortality showed a log-linear association with each other, although there was no log-linear association observed among ER-positive cancers.