Is Mohs micrographic surgery more effective than wide local excision in reducing recurrence for DFSP?

Dermatofibrosarcoma protuberans (DFSP) is a rare, indolent but locally aggressive cutaneous tumour, most commonly affecting adults. The commonest site affected is the trunk, followed by extremities and then head and neck. DFSP rarely metastasises, however it has a high rate of local recurrence following wide local excision (WLE) even after apparently adequate surgical margins. There is wide variation in current surgical management of DFSP across the UK. Conventional management of DFSP has been by WLE (with variable margins ranging between 1 cm to 5 cm), which is reported to confer recurrence rates of as high as 60%, depending on tumour location and surgical margins used.

In contrast, treatment of DFSP using Mohs micrographic surgery (MMS), which enables 100% tumour margin control, has been reported to achieve recurrence rates up to to 8.3%. However, these data are based on retrospective and/or non-comparative studies that are heterogeneous and potentially subject to bias. There have been no randomised controlled trials comparing different surgical treatments and little robust long-term follow up data is available.

Currently there are no consensus UK guidelines for the management of DFSP.

A multi-centred RCT across UK Specialist Skin Cancer Multidisciplinary Team (SSMDT) centres investigating recurrence rates at 3 years for DFSP comparing MMS and WLE. Secondary outcomes include distant metastases, patient reported outcomes, patient experience rating, cosmetic appearance, adverse events and cost-effectiveness.

As a result, the UK Dermatology Clinical Trials Network (UK DCTN) DFSP Study group have collaborated with the NCRI Non-Melanoma Skin Cancer Subcommittee Group to undertake feasibility work comprising the following:

1) A national retrospective case-notes review analysing management of DFSP by SSMDTs across the UK, which will inform trial design.

2) Clinician survey to determine the broad treatment strategies used by SSMDTs and Sarcoma MDTs and to assess clinician willingness to recruit patients to this trial.

3) A patient survey to determine the patient perspective on previous treatment, to assess acceptability of our proposed trial and to guide development of the trial by identifying barriers to recruitment.

In addition, we are planning further feasibility work to investigate:

1) Disease-specific patient reported outcome measures – this will involve structured patient interviews – ethical approval will be sought for this aspect of the project. If you have any patients who have experienced DFSP and would be willing to participate in interviews, please contact rubeta.matin@ouh.nhs.uk

2) Cost-effective analysis – this work is being carried out in conjunction with a health economist

3) Further statistical analysis of the reported literature to determine the probability of distribution effect of WLE versus MMS.

The national audit, clinician and patient surveys have been completed. The work will be published in due course.