PRECLINICAL STUDY Changes in shoulder muscle size and activity following treatment for breast cancer Delva R. Shamley Æ Ragavan Srinanaganathan Æ Rosamund Weatherall Æ Reza Oskrochi Æ Marion Watson Æ Simon Ostlere Æ Elaine Sugden Received: 15 November 2006 / Accepted: 25 November 2006 Ó Springer Science+Business Media B.V. 2006 Abstract Background Morbidity of the shoulder after breast cancer is a well-known phenomenon. MRI studies have shown muscle morbidity in cervical cancer and prostate cancer. In breast cancer clinical observations and patient reports include muscle morbidity in a number of muscles acting at the shoulder. Several of these muscles lie in the field of surgery and radiotherapy. Timed interaction between muscles that stabilise the shoulder and those acting as prime movers is essential to achieve a smooth scapulohumeral rthythm during functional elevation of the arm. Method: Cross-sectional study Seventy-four women treated for unilateral carcinoma of the breast were included in the study. All patients filled out the Shoulder Pain and Disability Index (SPADI). EMG activity of four muscles was recorded during scaption on the affected and unaffected side. Muscle cross sec- tional area and signal intensity was determined from MRI scans. The association between EMG and cova- riates was determined using multiple linear regression techniques. Results Three of the 4 muscles on the affected side demonstrated significantly less EMG activity, particu- larly when lowering the arm. Upper trapezius demon- strated the greatest loss in activity. Decreased activity in both upper trapezius and rhomboid were signifi- cantly associated with an increase in SPADI score and increased time since surgery. Pectoralis major and minor were significantly smaller on the affected side. Conclusion Muscles affected in the long term are the muscles associated with pain and disability yet are not in the direct field of surgery or radiotherapy. Primary muscle shortening and secondary loss of muscle activ- ity may be producing a movement disorder similar to the ‘Dropped Shoulder Syndrome’. Exercise pro- grammes should aim not only for range of movement but also for posture correction and education of potential long-term effects. Keywords Breast cancer Á Electromyography Á MRI Á Shoulder Introduction Breast screening programmes have allowed more con- servative approaches to surgery and radiotherapy for women diagnosed with breast cancer [1]. Despite the use of less extensive surgery and where possible the avoidance of radiotherapy to the axilla, there is still morbidity affecting the shoulder [2–4]. Radiotherapy is standard practice for patients receiving conservative surgery and those at risk of recurrence, and is generally D. R. Shamley (&) Á R. Srinanaganathan Department of Physiotherapy, School of Health and Social Care, Oxford Brookes University, Jack Straws Ln, Marston, Oxfordshire OX3 0FL, UK e-mail: drshamley@brookes.ac.uk R. Weatherall Centre for Statistics in Medicine, Oxford, UK R. Oskrochi Department of Mathematical Sciences, Oxford Brookes University, Oxford, UK M. Watson Á S. Ostlere MRI Unit, Nuffield Orthopaedic Hospital, Oxford, UK E. Sugden Department of Oncology, Churchill Hospital, Oxford, UK 123 Breast Cancer Res Treat DOI 10.1007/s10549-006-9466-7