Is there an association between breast cancer and incident adhesive capsulitis of the shoulder? A retrospective cohort study from Germany.

PURPOSE: Preliminary data suggest that women with breast cancer are at particularly high risk of adhesive capsulitis of the shoulder. Therefore, this study aimed to investigate the potential association between breast cancer and adhesive capsulitis in adults from Germany. METHODS: This retrospective cohort study included all women aged ≥ 18 years who were diagnosed for the first time with breast cancer in one of 1,274 general practices in Germany between January 2000 and December 2018 (index date). Women without breast cancer were matched (1:1) to those with breast cancer using a propensity score based on age at the index date, index year, and the average number of medical consultations per year during the follow-up. In women without breast cancer, the index date was a randomly selected visit date between 2000 and 2018. The association between breast cancer and the 10-year incidence of adhesive capsulitis was studied using Kaplan-Meier curves and a Cox regression model adjusted for age and several comorbidities. RESULTS: There were 52,524 women included in this study (mean [SD] age 64.2 [12.9] years). The 10-year incidence of adhesive capsulitis was 3.6% in both the group with and the group without breast cancer (log-rank p-value = 0.317). The Cox regression analysis further showed no significant association between breast cancer and adhesive capsulitis (HR = 0.96, 95% CI = 0.86-1.08). CONCLUSION: In this sample of women from Germany, breast cancer was not significantly associated with adhesive capsulitis. Although the present preliminary findings are reassuring, general practitioners should regularly assess shoulder function in breast cancer survivors.