Shoulder morbidity after treatment for breast cancer is bilateral and greater after mastectomy

A recent study in our laboratory found significant differences in scapular kinematics between the affected and unaffected sides of women reporting shoulder pain following treatment for breast cancer. An earlier smaller study from our laboratory found reduced muscle activity from four key muscles and an association with greater shoulder pain and disability. The aims of this study were to: correlate altered muscle activity from a larger sample with observed movement deviations; compare within subject movement and muscle deviations in survivors with healthy variation; explore the impact of a mastectomy vs. a wide local excision (WLE) on the observed deviations.

Cross-sectional study. One hundred and fifty-five women treated for unilateral carcinoma of the breast and 21 age-matched healthy women were included in the study. All patients filled out the Shoulder Pain and Disability Index (SPADI). Three-dimensional (3D)-kinematic data and EMG muscle activity were recorded during scaption on the affected and unaffected side. The association between kinematic data, EMG data, SPADI and covariates was determined using a two stage, random effects mixed multiple regression technique.

All scapula kinematic and muscle EMG parameters in both arms were altered in breast cancer survivors when compared to healthy participants. Altered movement patterns were different for left vs. right side affected. Mastectomy patients demonstrated greater movement deviations and reported significantly higher levels of pain than WLE patients.

Shoulder morbidity is bilateral, greater in patients having a mastectomy and is present for up to six years post-surgery. This study and others now provide ample evidence to support prospective surveillance programmes that can be integrated into Survivorship Programmes.