Effects of mechanical stimulation on mastectomy scars within 2 months of surgery : a single-center, single-blinded, randomized controlled trial

Abstract

Background: One common complication after mastectomy is thickened scars at the surgical site that impair shoulder function. This study aimed to investigate the effects of mechanical stimulation on scar appearance, arm function, and quality of life of breast cancer survivors after mastectomy. Methods: This was a single-center, single-blinded (assessor), randomized controlled trial with a 3-month follow-up. Women who had undergone mastectomy in the preceding 6 weeks for breast cancer were randomly allocated to an experimental group and a control group by permuted block randomization (block size=6). The experimental group received conventional treatment (mobilization and strengthening exercises) and mechanical stimulation applied to the mastectomy scar twice a week for 6 weeks (12 sessions). The control group received 12 sessions of conventional treatment only. Primary outcome measures included the Vancouver Scar scale (VSS) to assess scar quality. The secondary outcomes were spectrophotometry, the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire; shoulder range of motion; the Numeric Pain Rating scale; hand grip strength; and Functional Assessment of Chronic Illness Therapy–Breast Cancer (FACT-B). Results: One hundred and eight participants were equally randomized to 2 groups. All follow-up assessments were completed in September 2018. Intention-to-treat analysis revealed a significant group × time interaction on the VSS (η² = 0.161, p < 0.001), DASH (η² = 0.060, p = 0.003), and FACT-B functional well-being scores (η² = 0.033, p = 0.034), indicating that the experimental group (n=54) showed greater improvement in these outcomes than the control group (n=54). Post-hoc analysis showed that the improvements in the VSS and DASH scores remained apparent at the 3-month follow-up. Other outcomes did not yield significant group × time interaction. No adverse effects were reported. Conclusion: The addition of mechanical stimulation to a conventional intervention program improved scar appearance, arm function, and functional well-being compared with conventional intervention alone.