A Phase 2 interventional study of Capsaicin 8% Patch and Serratus Plane Block in Post-Mastectomy Neuropathic Pain Syndrome, sponsored by Centre Oscar Lambret. Recruiting at 1 site in France. Open to female participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-17.
Sponsored by Centre Oscar Lambret · Phase 2, Interventional, and Treatment
The goal of this phase II clinical trial is to study the effectiveness of a treatment with Serratus Plane Block (SPB) or Botox-A in comparison with capsaicin for the control of chronic neuropathic pain of post-mastectomy syndrom, that is not adequately managed by systemic treatment alone. The primary outcome will be the pain evaluation at 8 weeks.
123 patients with chronic neuropathic pain of post-mastectomy syndrom insufficiently relieved by systemic treatment alone will be recruited over 24 months at the Centre Oscar Lambret.
Patients will be randomly assigned to one of three treatment groups (41 patients per group):
Capsaicin Botulinum toxin A SPB
Patients will be followed for 24 weeks after the study treatment. The follow-up will include remote evaluation and 2 medical visits during which pain and quality of life will be assessed.
SerCaBot is a randomized, open-label, phase II clinical trial designed to evaluate the efficacy of a treatment with Serratus Plane Block (SPB) or Botox-A compared to capsaicin for the control of chronic neuropathic pain of post-mastectomy syndrom, that is not adequately managed by systemic treatment alone.
123 patients with will be recruited over 24 months at the Centre Oscar Lambret.
This clinical trial will be proposed to patients with chronic neuropathic pain of post-mastectomy syndrome that is not adequately managed by systemic treatment alone.
After consent, an inclusion assessment will be carried out including clinical examination, anamnesis, pain assessment (questionnaires PCS, NPS, DN4, NPSI and collect of antalgic treatment) and evaluation of quality of life (questionnaire SF12) and depression (questionnaire HADS).
Patients will then be randomly assigned to one of three treatment groups : Capsaicin, Botox-A, SPB (41 patients per group). The randomization will be balanced 1:1:1, controlled by minimisation (with a random factor set at 0.8) for the distribution of the following factors:
The study treatment will be administered 1 to 2 weeks after randomization. Treatment will be stopped prematurely in the event of unacceptable toxicity or complication. In each group, a repeat of the treatment may be considered after 12 weeks if further pain control is required. In the SPB group, a repeat is also possible every 2 weeks.
Patients will be followed for 24 weeks after the study treatment. Follow-up will include:
Patients will withdraw from the study after the 24 week medical visit. Early withdrawal will be possible in case of patient's decision of withdrawal, breast surgery during follow-up, or death.
Unilateral breast cancer treated by total or partial mastectomy:
Presenting moderate to severe chronic neuropathic pain, defined by:
Exclusion Criteria :
Chronic pain of another etiology such as:
Clinical signs or medical history leading to the diagnosis of:
Participants in this arm will receive an 8% capsaicin patch in a single treatment session in addition to a systemic treatment that has been ongoing for at least 4 weeks. If pain persists, the capsaicin patch application may be repeated at 12 weeks.
Drug: Capsaicin 8% Patch
Participants in this arm will undergo a Serratus Plane Block (SPB), a local anesthetic injection administered by a trained anesthesiologist, in addition to a systemic treatment that has been ongoing for at least 4 weeks. The SPB can be repeated every two weeks up to a maximum of four sessions within the initial 8-week period if pain persists. A repeat treatment may be considered at 12 weeks if further pain control is needed. This intervention aims to provide extended pain relief for neuropathic pain in post-mastectomy patients
Procedure: Serratus Plane Block
This arm involves administration of Botulinum Toxin A (Botox-A) at the site of pain, in addition to a systemic treatment that has been ongoing for at least 4 weeks. If pain remains unresolved, the injection may be repeated at 12 weeks. Botox-A is used here as a local, long-lasting analgesic intervention aimed at reducing chronic neuropathic pain in patients post-mastectomy.
Procedure: Botulinum Toxin A
One or two capsaicin patch (8%) are applied for 60 minutes to the site of neuropathic pain, in day-hospital. An oral, antalgic pre-medication may be done with one of the following medications (alone or association): paracetamol 1g, nefopam 30 mg, tramadol 100 mg, morphine 10mg, oxycodone 5mg. Capsaicin will be administered in addition to a systemic treatment that has been ongoing for at least 4 weeks. If pain persists, the capsaicin patch application may be repeated at 12 weeks.
Also known as: Qutenza®
The Serratus Plane Block (SPB) is a nerve block performed by a trained anesthesiologist to provide localized pain relief. It involves the injection of a local anesthetic: Maximum 150 mg naropeine combined with 150 μg clonidine hydrochloride into the serratus anterior plane under ultrasound guidance. An anesthesiologist will perform the procedure in a post-interventional recovery room, with light sedation.The SBP will be carried out in addition to a systemic treatment that has been ongoing for at least 4 weeks. The SPB may be repeated every two weeks up to four times in the initial 8-week period, with an additional repeat at 12 weeks if pain control remains insufficient.
Also known as: SPB
Botulinum Toxin A (Botox-A) is injected into the affected area, with a total of 300 units administered across up to 60 injection sites. An anesthesiologist will perform the procedure in a post-interventional recovery room, with light sedation. This intervention will be carried out in addition to a systemic treatment that has been ongoing for at least 4 weeks, and is aimed at providing prolonged pain relief for post-mastectomy neuropathic pain. Light sedation is provided, and injections may be repeated at 12 weeks if necessary.
Also known as: Botox-A, Botox
Pain assessment using Numerical Pain Scale (END)
The primary outcome measure is pain assessed by self-evaluation using the Numerical Pain Scale (END) ranging from 0 (no pain) to 10 (worst pain imaginable) at rest, evaluated 8 weeks after treatment (or 9 weeks after randomization if treatment was not performed). The patient's self-assessment reflects individual treatment efficacy. In case of treatment interruption due to immediate intolerance or technical issues, the baseline END will be considered for the primary analysis.
Time frame: 8 weeks after treatment initiation, or the closest measurement within +/- 1 week if the 8-week data is missing.
Success of Pain Control
Defined as a reduction in pain of 3 points or more on the Numerical Pain Scale (END) at 8 weeks, with failure indicated in other cases.
Time frame: Assessed at 8 weeks post-treatment.
Evolution of Pain Scores
Change in pain levels as self-reported by the patient using the END at 1, 2, 4, 6, 8, and 24 weeks after treatment (and at 13, 14, 16, and 18 weeks if treatment is repeated at 12 weeks).
Time frame: Assessed at multiple time points: 1, 2, 4, 6, 8, and 24 weeks.
Neuropathic Component Evaluation
Change in neuropathic symptoms assessed via the Neuropathic Pain Symptom Inventory (NPSI) at 1, 2, 4, 6, 8, and 24 weeks after treatment (and at 13, 14, 16, and 18 weeks if treatment is repeated at 12 weeks).
Time frame: Assessed at multiple time points: 1, 2, 4, 6, 8, and 24 weeks.
Early Treatment Failure
Early failure of local analgesic treatment defined by failure to perform the procedure (due to intolerance or technical issues) or failure to control pain as evaluated at 7 and 14 days post-procedure.
Time frame: Assessed at 7 and 14 days post-treatment
Modification of introduction of New Analgesic Treatment
Documentation of any change in systemic treatement or introduction of new analgesic treatments (e.g., antiepileptics, antidepressants, opioids), with dosages collected at 1, 2, 4, 6, 8, and 24 weeks after treatment (and at 13, 14, 16, and 18 weeks if treatment is repeated).
Time frame: Assessed at multiple time points: 1, 2, 4, 6, 8, and 24 weeks.
Adverse Events
Monitoring of adverse events possibly related to the treatment (capsaicin, botulinum toxin type A, or SBP block) during and after the local procedure, graded according to NCI-CTCAE v5.0.
Time frame: From study treatment to 24-weeks follow-up
HADS Scale Evaluation
Assessment of anxiety and depression using the Hospital Anxiety and Depression Scale (HADS) at baseline, 8 weeks, and 24 weeks.
Time frame: Assessed at baseline, 8 weeks, and 24 weeks.
Quality of Life Assessment
Evaluation of health-related quality of life using the SF12 scale at baseline, 8 weeks, and 24 weeks.
Time frame: Assessed at baseline, 8 weeks, and 24 weeks.
Patient General Impression of Change (PGIC)
Self-assessment of change in condition from 1 (no change or worse) to 7 (considerable improvement) measured at 8 weeks and 24 weeks.
Time frame: Assessed at 8 weeks and 24 weeks
Plan to share: No
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