Aim: To determine if women with multiple sclerosis (MS) reported an increased risk of breast cancer compared with the general female population.
Patients and methods: We conducted a systematic review and meta-analysis of observational cohort studies. We performed a search in PubMed/Medline of studies where standardized incidence ratios (SIRs) were provided. Overall estimates of the SIRs (meta-SIRs) were calculated using DerSimonian-Laird random effects models. Sources of heterogeneity were explored by means sub-groups analyses.
Results: Five studies met the inclusion criteria. Women with MS were not associated with increased risk of overall (meta-SIR = 0.80; 95% confidence interval, 95% CI = 0.61-1.06) and breast cancers (meta-SIR = 1.02; 95% CI = 0.75-1.40). These differences did not turn out to be statistically significant. A high degree of heterogeneity between studies was found (I2 = 88.7% and I2 = 75.3%, respectively).
Conclusions: The data shown here suggest a similar risk of breast cancer in women with MS when compared to the general population. Further research is required to evaluate the role of specific risk factors at cancer sites such as effects of treatments used in the management of MS patients.