Bilateral Ultrasound Assessment of the Pectoralis Major and Latissimus Dorsi Muscles in Women in the Non-Active Phase of Breast Cancer

To assess bilateral alterations in the pectoralis major and latissimus dorsi muscles in women in the non-active phase of breast cancer, focusing on muscle and tendon thickness and strength using ultrasound and dynamometry. An observational study included 15 women (mean age: 52.7 years) with non-active phase breast cancer. Bilateral ultrasound measurements assessed pectoralis major and latissimus dorsi muscle thickness and pectoralis major tendon thickness. Maximum muscle strength was measured with a digital dynamometer. The Wilcoxon signed-rank test analyzed differences between affected and unaffected sides. No statistically significant differences were observed in the thickness of the pectoralis major and latissimus dorsi muscles or the pectoralis major tendon between the affected and unaffected sides. However, a significant reduction in the maximum strength of the pectoralis major muscle was identified on the affected side ( P = .003), while no significant differences were found in the strength of the latissimus dorsi muscle. Breast cancer treatment significantly reduces pectoralis major muscle strength without observable changes in muscle or tendon thickness. Findings highlight the need for targeted rehabilitation to improve strength posttreatment.