Botulinum Toxin Type A for Refractory Post-Mastectomy Pain Syndrome: A Retrospective Study of Clinical Outcomes Within a Rehabilitation Framework

Post-mastectomy pain syndrome (PMPS) is a frequent and disabling complication among breast cancer survivors. A subgroup of patients remains refractory to conventional rehabilitation, emphasizing the need for new therapeutic strategies. This study evaluated the clinical impact of botulinum toxin type A (BTX-A) on pain and function in individuals with refractory PMPS. This retrospective cohort study included 39 women with refractory PMPS who reported persistent pain despite conservative rehabilitation. All individuals received ultrasound-guided BTX-A injections, with follow-up at 1, 3, and 6 months, and additional injections offered at follow-up visits according to clinical evolution. Pain, disability, and shoulder mobility were assessed at baseline and at 1, 3, and 6 months postinjection using the Numerical Pain Rating Score, Shoulder Pain and Disability Index, and goniometric measurement of range of motion. Clinical relevance was evaluated using minimal clinically important difference, and patient acceptable symptom state. Pain and disability improved at all follow-up assessments, while shoulder mobility showed modest gains. Most individuals achieved clinically meaningful pain reduction at 1 and 3 months, with functional gains reflected in Shoulder Pain and Disability Index scores. No adverse events were reported. BTX-A injections used within a rehabilitation framework were associated with clinically meaningful reductions in pain and disability in individuals with refractory PMPS. These findings support a potential complementary role for BTX-A in carefully selected individuals with limited therapeutic options, a population with unmet needs in cancer rehabilitation. Future studies are needed to define optimal treatment timing and evaluate long-term outcomes.