Predisposing Factors for Idiopathic Granulomatous Mastitis: A Large Prospective Multicentric Study

Idiopathic granulomatous mastitis (IGM) is a chronic breast disease with unknown pathophysiological and clinical aspects. Therefore, we designed this multi-center prospective case-control study to explore and clarify the risk factors with an acceptable sample size.

From March 2021 to December 2023, five hundred-four women with a histologically proven IGM were entered into the IGM group and 504 women with healthy breasts were included in the control group across nine centers. Participants' information was obtained by trained staff. Multivariate binary logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (CI) for the associations between variables and IGM.

The mean age of all participants was 34.92 ± 7.12 yr. The previous history of diseases as a whole, was significantly higher in the IGM group (33.1%) compared with the control group (26.6%). Logistic regression showed that previous lactation (OR= 7.51, 95% CI= 2.37-23.77) and a positive history of diabetes (OR = 4.23, 95% CI= 1.32-13.51) had a positive association with IGM, while OCP use (OR = 0.70, 95% CI= 0.52-0.93) was associated with IGM reversely.

The history of breastfeeding and not its duration is associated with a 7-fold increase in the rate of IGM. Furthermore, previous history of diabetes is a risk factor, while OCP use is a protective factor against IGM. We are designing another study to further investigate the relationship between breastfeeding, milk stasis, and IGM, based on our findings.