Breast cancer risk in hyperprolactinemia: a population-based cohort study and meta-analysis of the literature
ObjectiveTo enhance the precision of the risk estimate for breast cancer in hyperprolactinemia patients by collecting more data and pooling our results with available data from former studies in a meta-analysis.DesignPopulation-based cohort study and meta-analysis of the literature.MethodsUsing nationwide registries, we identified all patients with a first-time diagnosis of hyperprolactinemia during 1994–2012 including those with a new breast cancer diagnoses after the start of follow-up. We calculated standardised incidence ratios (SIRs) as a measure of relative risk (RR) using national cancer incidence rates. We performed a meta-analysis, combining data from our study with data in the existing literature.ResultsWe identified 2457 patients with hyperprolactinemia and 20 breast cancer cases during 19 411 person-years of follow-up, yielding a SIR of 0.99 (95% CI 0.60–1.52). Data from two additional cohort studies were retrieved and analyzed. When the three risk estimates were pooled, the combined RR was 1.04 (95% CI 0.75–1.43).ConclusionsWe found no increased risk of breast cancer among patients with hyperprolactinemia.