Prevalence and mechanisms of subacromial impingement in breast cancer patients after breast-conserving surgery and radiation therapy: a case-cohort study.

Purpose: Subacromial impingement is a painful shoulder disorder, which may be common after breast cancer treatment. A previous study showed a high prevalence after mastectomy but prevalence after conservatively treated patients is unknown. Impingement mechanisms in breast cancer survivors have not been studied.

Methods: Twenty-four breast cancer survivors who had undergone breast-conserving surgery without axillary lymph node dissection followed by radiation therapy, and 12 cancer-free controls were included. Breast cancer survivors were grouped by the presence of subacromial impingement pain. The subacromial space and the supraspinatus tendon were imaged using ultrasound on the treated side in the breast cancer survivors and a randomly chosen side in controls. In these images, the width of the subacromial space, thickness of the supraspinatus tendon and combined thickness of the supraspinatus tendon and surrounding soft tissues were measured.

Results: Subacromial impingement prevalence among breast cancer survivors was 54%. The width of the subacromial space and the thickness of the supraspinatus tendon were not different in breast cancer survivors with subacromial impingement compared to breast cancer survivors without subacromial impingement and controls. Combined thickness of the supraspinatus tendon and surrounding soft tissues was grater in breast cancer survivors with subacromial impingement.

Conclusion: Prevalence of subacromial impingement is high, even in the most conservatively treated breast cancer patients. The presence of subacromial impingement pain is unrelated to width of the subacromial space, but greater thickness of the supraspinatus tendon and surrounding soft tissue may be part of the impingement mechanism.