Risk of Premenopausal and Postmenopausal Breast Cancer among Multiple Sclerosis Patients.

Mohammadhossein Hajiebrahimi,Shahram Bahmanyar,Scott Montgomery,Sarah Burkill,Masaru Katoh

doi:10.1371/journal.pone.0165027

Abstract

ObjectiveTo investigate risk of premenopausal and postmenopausal breast cancer among Multiple Sclerosis (MS) patients, considering tumor stage.MethodsThe Swedish Patient Register identified 19,330 women with MS between 1968 and 2012, matched individually with a cohort of 193,458 without MS. Matching variables were year of birth, sex, region of residence and vital status at the time of diagnosis. The cancer register identified 471 and 5,753 breast cancer cases among the MS and non-MS cohorts, respectively. Cox proportional hazard models estimated hazard ratios (HR) and 95% confidence intervals (CI) for premenopausal and postmenopausal breast cancer.ResultsOverall risk of postmenopausal breast cancer was 13% higher among MS patients compared with women without MS (HR = 1.13, 95% CI 1.02–1.26). Stratified analyses showed that the risk was statistically significantly increased in women diagnosed between 1968 and 1980 and those who were diagnosed at age 65 or older age. We observed a non-statistically significant risk only for stage 0–1 postmenopausal breast cancer (HR = 1.17, 95% CI 0.93–1.48). MS was not associated with premenopausal breast cancer.ConclusionThe modest increased risk of postmenopausal breast cancer in women with MS may be due to surveillance bias, where contact with health services for one disease increases the risk of a second diagnosis being recorded.

Highlights

Multiple Sclerosis is a chronic inflammatory disease of the central nervous system which is more common among the women[1, 2]
Overall risk of postmenopausal breast cancer was 13% higher among Multiple Sclerosis (MS) patients compared with women without MS (HR = 1.13, 95% confidence intervals (CI) 1.02–1.26)
Stratified analyses showed that the risk was statistically significantly increased in women diagnosed between 1968 and 1980 and those who were diagnosed at age 65 or older age

Summary

Introduction

Multiple Sclerosis is a chronic inflammatory disease of the central nervous system which is more common among the women[1, 2]. The overall risk for cancer seems to be lower among MS patients compared with those without MS[3], the risk of some site-specific cancers, such as bladder cancer, is increased among these patients[3, 4]. Findings from previous studies on the association between MS and breast cancer have yielded inconsistent results: the risk of breast cancer was increased [4,5,6,7] or there was no association [3, 8, 9]. Previous studies that looked at tumor size [4] did not take other tumor characteristics into account, such as tumor stage or menopausal status. Our aim was to assess the risk of breast cancer in MS patients, including categorization of breast cancer by menopausal status and tumor stage

Methods

Discussion

Conclusion