Larger Surgical Margins Not Needed for Dermatofibrosarcoma Protuberans

Ibrahim S. Alshaygy, MD, MSC

Smaller resection sites can effectively eradicate disease in patients with dermatofibrosarcoma protuberans (DFSP) with low rates of recurrence, explained Ibrahim S. Alshaygy, MD, MSC.

In a study led by Alshaygy, 196 patients with DFSP in the sarcoma unit of Mount Sinai Hospital in Toronto received resection surgeries utilizing margins of 2.5 cm to ensure complete removal of the tumor. DFSP is a rare cutaneous tumor of intermediate monoclonal dermal neoplasm, and it is known to be locally aggressive and infiltrative.

At a minimum 1-year of follow-up, results showed that with this method, 7.1% (n = 14) of patients were found to have positive margins, 4.1% (n = 8) of patients underwent radiation therapy, and 3.1% (n = 6) of patients were discharged without further treatment. During follow-up, 1 patient who had local recurrence at the time of referral did develop additional local recurrence, and another patient developed a lesion in another site. However, no recurrence was observed in all other patients.

“The most important thing [to remember] is that you don't have to [create a] big surgical margin, even if you have a big resection, to prevent [the tumor] from recurring,” said Alshaygy.

Additionally, there have been recent updates in the field of tenosynovial giant cell tumor (TGCT), which now includes therapeutic options for patients beyond surgery.

In an interview with OncLive^® during the 2019 Musculoskeletal Tumor Society Annual Meeting, Alshaygy, a clinical fellow in Orthopedic Oncology at Mount Sinai Hospital, discussed surgical developments in DFSP and TGCT.

OncLive^®: Could you discuss your study on surgical resection in DFSP?

Alshaygy: DFSP is a continuous tumor that is fairly uncommon, but has a high local recurrence rate. I'm presenting a new way of resection because with the recent literature, almost everyone is talking about wide margin resection. Our aim is to achieve a negative margin closer to the tumor. [Achieving a negative margin] is more sufficient to prevent local recurrence, which is in contrast to the standard literature that says we have to [resect] at least 5 cm. We also devised a new follow-up protocol depending on the pathological classification and grading for the tumor.

How are these data expected to impact the field?

It is expected to have quite a significant impact because in the standard practice, [surgeons] tend to go for a bigger, wider-section margin. We suggest a smaller incision. As long as you achieve a negative margin, that is more than enough and causes fewer adverse events, better cosmesis, and better functional outcomes for the patient.

Additionally, this new follow-up protocol can impact your clinic follow-up and patient follow-up regime, as it's going to save a lot of time for you and the patient.

What are the next steps of the study?

We are almost done with all of the data collection. We did the data analysis and we reached a good level of outcome. Now, we are trying to look into the grading and classification [of the tumor] and then publish it to the medical field. In our practice, we already established and adopted this follow-up protocol and this treatment modality, but it is good to generalize it to the population.

What is the key takeaway from this study?

To prevent [the tumor] from recurring, all you need is to have a negative margin—meaning that you remove the tumor with a small, thin layer of negative tissue, and that is enough. It doesn't have to be 5 cm, 1 cm, or even 0.5 cm. The study and data showed that [when you use this method], you don't have local recurrence.

Moving on to TGCT, what are some of the advances in treatment for these patients?

Recently, the standard of care is pure surgical resection and you have to [resect] to the negative margin to prevent and minimize the risk of local recurrences. There are some breakthroughs in targeted therapy.

What are your thoughts on the approval of pexidartinib (Turalio) in TGCT?

It's a good thing that it got approved by the FDA. I'm sure there are a lot of patients who are waiting for it and may benefit from it. Personally, I haven't given [pexidartinib] to any of my patients yet. If it is a good, safe, drug that was approved by the FDA, I don't see a reason not to give it to a patient to see if they can benefit from it.

Are there any precision medicine efforts in this field for clinical trials?

There are a lot of clinical trials ongoing now in the United States and Canada in targeted therapy, especially for patients who have consumed all the other medical options. Some of them have shown some efficacy. They passed the safety [phases]; they are looking at tumor size reduction and also [looking] to control the disease and prolong survival.

What do you want fellow physicians to know about this field and how it is evolving?

Medicine is evolving quickly and we need to keep up to improve the breakthrough in medicine and treatment for this patient population. [TGCT] is not that common in comparison with the general population, but it's a very important field that we need to address. We need to try and work hard, divert more funding and resources into research to try to find new therapies, and use different modalities to improve and prolong the survival of those patients.

Alshaygy I, Basile G, Mattei J-C, et al. Outcome after surgical treatment of dermatofibrosarcoma protuberans (DFSP): does it requires all this follow up? How much resection margin is enough? Presented at: 2019 Musculoskeletal Tumor Society Annual Meeting; October 2-4, 2019; Portland, OR. Abstract 4.