Magnitude of late effects of breast cancer treatments on shoulder function: a systematic review

Late effects of treatment for breast cancer on shoulder function have been documented by a number of investigators; however, many studies include only prevalence data. When comparisons are provided that assess differences between treatment groups, only P-values without magnitudes of effect are often reported. The purpose of this systematic review was to identify literature that could be used to examine the magnitude of late effects of breast cancer treatments on shoulder function with a particular focus on axillary lymph node dissection (ALND) and on radiotherapy. A comprehensive search of online databases was performed for research papers published between 1980 and 2008 that provided comparison data between treatment groups, between the affected and unaffected side of individuals, or between pre-operative and subsequent assessments 12 months or more after diagnosis of breast cancer. Papers that met inclusion criteria were reviewed using a methodological checklist. Standardized effect sizes were computed for continuous data; odds ratios and 95% confidence intervals were computed for dichotomous data if not already available. Twenty-two papers met the inclusion criteria. With a few exceptions, most analyses showed excess shoulder morbidity with breast cancer treatment, ALND, or radiotherapy. Although effect sizes varied, moderate to large effects predominated across the different outcomes. There is sufficient evidence of late effects of ALND or radiotherapy post-breast cancer to warrant careful attention to shoulder function across time in individuals who have had breast cancer. Implications for future shoulder dysfunction are discussed.