Breast Cancer Incidence in Sjögren Syndrome Patients.

The breast cancer risk profiles of SS (Sjögren syndrome) patients have shown inconsistent findings in different reports. A recent systematic review and meta-analysis indicated potential geographical variations in the link between pSS (primary Sjögren syndrome) and the risk of breast cancer. Patients with pSS from European countries exhibited a decreased likelihood of developing breast cancer, whereas an increased risk was observed in individuals from Asia and Argentina. A French study revealed that the incidence of breast cancer in pSS patients is lower. Therefore, we aimed to explore the incidence of breast cancer in SS or pSS through the TriNetX. Data were retrieved from 1 January 2018 to 31 December 2022. The outcome was the development of breast cancer, and Sjögren and non-Sjögren cohorts were compared. The hazard ratio (HR) and its 95% confidence interval (CI) of the outcomes were determined. A total of 5103 patients were in each cohort after propensity score matching (PSM). We found a slightly but non-significantly elevated risk of breast cancer incidence in the Sjögren cohort (HR: 1.079, 95% CI: 0.765-1.522). The subgroup analysis showed no difference in age, race, obesity, or diabetes mellitus status. We obtained similar findings in the sensitivity analyses for pSS patients and patients in different networks. The Sjögren cohort of white patients (3.343, 1.315-8.498) and non-obese patients (4.034, 1.309-12.42) had a significantly higher risk of breast cancer occurring in overlapping sites. The risk of estrogen receptor (ER)-positive breast cancer was significantly higher among the white patients in the Sjögren cohort (1.860, 1.031-3.353). Neither SS nor pSS was significantly related to an increased risk of breast cancer, and the results according to race were similar. The white and non-obese patients in the Sjögren cohort had a significantly higher risk of breast cancer occurring in overlapping sites. White patients in the Sjögren cohort had a significantly higher risk of ER-positive breast cancer. To our knowledge, this study is the first to explore the location and ER status of breast cancer in SS patients.