Chest wall pain as a late effect following radiotherapy for breast cancer: A systematic review of prevalence and risk factors.

Background: Breast cancer is the most commonly diagnosed cancer in women with approximately 60% receiving adjuvant radiotherapy. Despite advances minimising radiation dose to normal tissues, many women report post treatment pain affecting quality of life. Limited evidence on pain location, severity and risk factors for occurrence impacts clinical management. This systematic review identified studies reporting the prevalence of chest wall pain after breast cancer radiotherapy and explored associated risk factors. Methods: Searches of PubMed, Embase, CINAHL and Cochrane identified studies published between 2005 and 2025. Terms focused on breast cancer radiotherapy and chest wall pain, graded using either a clinician reported or patient reported outcome measure, more than three months post treatment. Abstracts and full texts were screened, appraised and a PRISMA diagram produced. Results: Eight studies met inclusion criteria: six observational cohort studies and two randomised trials, totalling 5509 patients. Pooled prevalence for chest wall pain was 34.0%. Mild pain was most commonly reported at 26.1%, while 5.7% reported moderate to severe pain. Temporal patterns could not be determined. Younger age, tumour bed boost and treated volume > 107% dose were identified as potentially associated factors, although findings were inconsistent. Seven studies used clinician reported outcomes; one study using patient reported measures reported higher chest wall pain prevalence. Meta-analysis was not performed due to significant heterogeneity in populations, radiotherapy techniques, and assessments. Discussion and conclusion: Chest wall pain is under recognised and poorly captured in breast radiotherapy research. It warrants evaluation as a distinct late effect. Further research is required to clarify prevalence, severity, trajectory, and risk factors.